11.5 Alt text and captions
10 min read•august 20, 2024
and are crucial for making web content accessible and inclusive. They provide textual descriptions of , aiding users with visual impairments and improving SEO. This topic explores the benefits, best practices, and implementation of alt text and captions in various contexts.
Effective alt text and captions enhance user experience, comply with accessibility guidelines, and support legal requirements. By understanding how to create and implement these elements, web designers and content creators can ensure their digital content is accessible to all users, regardless of their abilities or technology constraints.
Benefits of alt text
- Alt text, short for alternative text, provides a textual description of an image's content and purpose
- Aids in making web content more accessible and inclusive for all users, regardless of their abilities or how they access the web
- Serves as a vital source of information for users who rely on assistive technologies, such as , to navigate and understand web pages
Accessibility for screen readers
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- Screen readers are assistive technologies that convert text and image descriptions into synthesized speech or braille output
- Alt text enables screen reader users to understand the content and of images on a webpage
- Without alt text, screen reader users may miss out on important information conveyed through images
Improved SEO
- Search engines, like Google, use alt text to better understand the content and context of images on a webpage
- Including relevant and descriptive alt text can improve a website's search engine rankings and visibility
- Alt text provides an additional opportunity to include target keywords, enhancing the page's relevance for specific search queries
Graceful degradation without images
- In situations where images fail to load due to slow internet connections, browser settings, or other technical issues, alt text provides a fallback
- Alt text ensures that users can still understand the intended message or purpose of the image, even when the visual is not displayed
- Graceful degradation maintains the usability and accessibility of a webpage, regardless of the user's environment or technology constraints
Writing effective alt text
- Effective alt text should be concise, descriptive, and contextually relevant to the image and its purpose within the content
- Alt text should provide enough information to convey the essential meaning of the image without being overly verbose
- Best practices for writing alt text include using clear language, avoiding redundancy, and considering the image's role in the overall content
Describing visual content concisely
- Alt text should briefly describe the most important aspects of an image, focusing on the content and purpose rather than aesthetic details
- Use clear, concise language that conveys the essential information without being overly wordy or complex
- Examples of concise alt text: "Woman hiking on a mountain trail" or "Graph showing quarterly revenue growth"
Avoiding redundancy with captions
- When an image is accompanied by a caption that adequately describes its content, the alt text should not repeat the same information
- In such cases, the alt text can provide additional context or be left empty if the image is purely decorative
- Example: If a caption reads "Sunset over the ocean," the alt text might add context like "Silhouette of a sailboat against an orange sky"
Alt text length considerations
- While there is no strict character limit for alt text, best practices suggest keeping it relatively short and focused
- Screen readers may truncate or pause longer alt text, which can be disruptive for users
- Aim for alt text that is typically around 125 characters or less, while still providing adequate description
Blank alt attributes for decorative images
- For purely decorative images that do not convey meaningful content, the alt attribute should be included but left empty (alt="")
- This signals to screen readers that the image can be safely ignored, reducing cognitive load and improving the user experience
- Examples of decorative images include visual flourishes, borders, or spacers that do not contribute to the page's content
Alt text in HTML
- In HTML, the alt attribute is used to specify alternative text for an image
- The alt attribute is a required attribute for the
tag, and its value should be a concise description of the image<img> - Proper usage of the alt attribute is essential for creating accessible and SEO-friendly web content
Importance of alt attribute
- The alt attribute ensures that users can understand the content and purpose of an image, even if the image fails to load or the user relies on assistive technologies
- Including alt text is a fundamental aspect of web accessibility and is required for compliance with guidelines such as WCAG (Web Content Accessibility Guidelines)
- Search engines use alt text to index and understand images, which can positively impact a website's search engine rankings
Proper alt attribute syntax
- The alt attribute is added to the
tag, following the src attribute that specifies the image file path<img> - Example of proper alt attribute syntax:
<img src="image.jpg" alt="Description of the image"> - The alt text value should be enclosed in double quotes and should not contain any HTML tags or special characters
Empty vs missing alt attributes
- An empty alt attribute (alt="") is used for decorative images that do not convey meaningful content and can be safely ignored by assistive technologies
- A missing alt attribute, where the attribute is omitted entirely, is considered an accessibility error and should be avoided
- Images that are important for understanding the content should always have a descriptive alt text value
Benefits of captions
- Captions provide additional context and information about an image, video, or audio file, enhancing the user experience and accessibility
- While alt text is primarily intended for users who cannot see the visual content, captions benefit all users by offering supplementary details
- Captions can help improve user engagement, comprehension, and overall satisfaction with the content
Additional context beyond alt text
- Captions can provide more detailed information about an image or media file, expanding upon the brief description provided by alt text
- This additional context can include details such as the location, date, or significance of the content, or any relevant background information
- Example: A caption for a photograph might read, "Sunset at Malibu Beach, California, captured during the summer solstice in June 2022"
Improved accessibility for all users
- Captions benefit not only users with visual impairments but also those with cognitive disabilities, language barriers, or learning preferences
- By providing a text alternative to visual content, captions make the information more accessible and easier to comprehend for a wider audience
- Captions are particularly useful for users in sound-sensitive environments or those with hearing impairments when consuming video or audio content
Enhancing user engagement
- Well-written captions can pique users' interest and encourage them to engage more deeply with the content
- Captions can provide additional insights, context, or even a touch of humor, making the content more memorable and shareable
- By offering a more comprehensive and engaging experience, captions can increase user satisfaction and encourage longer visits to a website or application
Writing effective captions
- Effective captions should complement the visual content without being redundant or overly verbose
- Captions should be concise, informative, and styled appropriately to ensure readability and accessibility
- When writing captions, consider the purpose of the content, the target audience, and the overall tone and style of the website or application
Complementing visual content
- Captions should provide additional information that enhances the understanding or appreciation of the visual content
- Avoid simply restating what is already apparent in the image or media file; instead, offer supplementary details or context
- Example: Instead of a caption that reads "A red car," provide more context like "A vintage 1965 Ford Mustang in cherry red, parked outside a retro diner"
Captions vs subtitles
- Captions and subtitles serve different purposes and should not be used interchangeably
- Captions provide additional descriptive information about visual content, while subtitles are a text alternative for the spoken content in a video or audio file
- Subtitles are typically a transcription of the dialogue or narration, often used for translation purposes or to assist users who are deaf or hard of hearing
Optimal caption length and style
- Captions should be concise and easily readable, typically no more than a few sentences in length
- Use clear, simple language and avoid jargon or complex terminology unless necessary for the target audience
- Ensure that the caption text is visually distinct from the surrounding content, using appropriate font size, color, and contrast
- Consider the placement of captions, ensuring they do not obscure important parts of the image or interfere with other text elements
Implementing captions
- Captions can be implemented in various formats and file types, depending on the type of media and the platform or CMS being used
- Proper association of captions with their corresponding media files is essential for accessibility and usability
- Different approaches may be required for implementing captions for audio content versus video content
Caption formats and file types
- Captions can be implemented using various file formats, such as .srt (SubRip Subtitle), .vtt (WebVTT), or .smi (SAMI)
- The choice of file format may depend on the specific requirements of the media player or platform being used
- Some platforms, like YouTube, offer built-in tools for adding and editing captions directly within their interface
Associating captions with media
- To ensure that captions are properly displayed and synchronized with the media content, they must be correctly associated with the corresponding media file
- This can be achieved through the use of HTML5 media elements, such as
and<video>
, and their child<audio>
element<track> - The
element is used to specify the caption file and its attributes, such as the language and label<track>
Captions for audio vs video
- While the general principles of caption writing and implementation apply to both audio and video content, there are some differences to consider
- For audio content, captions may include speaker identification, sound effects, and other relevant non-speech information
- Video captions may need to be synchronized with the visual content and should be placed in a way that does not obstruct important visual elements
- When creating captions for video, it's essential to consider the timing and pacing of the captions to ensure they are readable and do not overwhelm the viewer
Alt text and captions in CMSs
- Many content management systems (CMSs) offer built-in features or plugins for adding and managing alt text and captions
- These tools can help streamline the process of creating accessible content and ensure consistency across a website or application
- Some CMSs may also offer automated tools for generating alt text or captions, though these should be reviewed and edited by a human for accuracy and context
Inputting alt text in WordPress
- WordPress, one of the most popular CMSs, allows users to add alt text to images through the Media Library or when inserting an image into a post or page
- To add alt text in WordPress, click on an image in the Media Library or within the post/page editor, and fill in the "Alternative Text" field in the attachment details sidebar
- WordPress also provides fields for adding captions and descriptions to images, which can be displayed alongside the image on the front end of the website
Adding captions in popular CMSs
- Other popular CMSs, such as Drupal, Joomla, and Shopify, also offer methods for adding captions to images and media files
- In Drupal, captions can be added using the Media module or through custom fields, depending on the specific configuration of the website
- Joomla allows users to add captions to images through the built-in Image field type or by using third-party extensions
- Shopify provides an "ALT Text" field for images and a "Caption" field for adding descriptive text to be displayed below the image
Automated alt text and caption tools
- Some CMSs and third-party tools offer automated solutions for generating alt text or captions using artificial intelligence (AI) or machine learning (ML) algorithms
- While these tools can be helpful for quickly generating basic descriptions, they should not be relied upon entirely for creating accurate and contextually relevant alt text and captions
- It's important to review and edit automatically generated alt text and captions to ensure they accurately convey the intended message and purpose of the visual content
Legal requirements
- Providing alt text and captions is not only a best practice for accessibility and user experience but also a legal requirement in many jurisdictions
- Failure to comply with accessibility laws and guidelines can result in legal consequences, financial penalties, and damage to a brand's reputation
- Understanding and adhering to the relevant legal requirements for alt text and captions is essential for creating inclusive and compliant digital content
ADA compliance for alt text
- The Americans with Disabilities Act (ADA) requires that all public-facing digital content be accessible to individuals with disabilities, including those who use assistive technologies
- Under the ADA, images must have accurate and descriptive alt text to ensure that users with visual impairments can access and understand the content
- Failure to provide alt text for important images can be considered a violation of the ADA and may result in legal action against the website owner or organization
WCAG guidelines for captions
- The Web Content Accessibility Guidelines (WCAG) provide a set of international standards for creating accessible digital content, including guidelines for captions
- WCAG 2.1 Success Criterion 1.2.2 (Captions - Prerecorded) requires that all prerecorded audio content in synchronized media have captions, with some exceptions for specific situations
- To meet , captions must be accurate, synchronized with the audio, and include all relevant non-speech information, such as speaker identification and sound effects
Potential consequences of non-compliance
- Non-compliance with accessibility laws and guidelines can result in a range of consequences, depending on the jurisdiction and the specific circumstances
- Potential consequences may include:
- Lawsuits and legal action brought by individuals or advocacy groups
- Financial penalties and fines imposed by regulatory bodies
- Damage to the brand's reputation and public image
- Loss of business and revenue due to inaccessible content
- To mitigate these risks, organizations should prioritize accessibility and ensure that all digital content, including images and media files, meets the required standards for alt text and captions
Key Terms to Review (18)
ADA Compliance: ADA compliance refers to the requirements set by the Americans with Disabilities Act (ADA) that mandate equal access to services and information for individuals with disabilities. This means that websites, apps, and other digital content must be designed to accommodate users with varying abilities, ensuring that everyone can engage with digital environments effectively. Key elements include the use of alt text for images and captions for videos, which are essential for making content accessible to those who rely on assistive technologies.
Alt text: Alt text, short for alternative text, is a written description that is added to an image on a webpage or digital content. It serves as a critical accessibility feature, allowing users who cannot see the image to understand its context and meaning through screen readers or other assistive technologies. This text not only enhances the user experience but also plays a role in SEO, helping search engines understand the content of images.
Captioning software: Captioning software is a type of technology that enables the creation, editing, and display of text captions that accompany video content. This software plays a crucial role in making videos accessible to individuals with hearing impairments by providing a textual representation of spoken dialogue and relevant audio cues. It often includes features that allow users to synchronize text with video playback and customize caption appearance for better readability.
Captions: Captions are textual descriptions or explanations that accompany visual media, such as images, videos, or infographics. They serve to provide context, enhance understanding, and offer accessibility for individuals who may not be able to perceive the visual elements effectively. Captions play a critical role in effective communication, especially in digital content where they can clarify the message being conveyed.
Conciseness: Conciseness refers to the quality of being brief and to the point while still conveying the necessary information. It is about eliminating unnecessary words and redundancy, allowing for clear communication that respects the audience's time and attention. This quality is especially crucial when creating alt text and captions, as it ensures that essential details are conveyed without overwhelming or confusing the reader.
Content strategy: Content strategy is the planning, development, and management of content—text, images, videos, and other media—created for a specific audience and purpose. This involves understanding audience needs, aligning content with business goals, and ensuring consistency across different platforms, all while focusing on creating valuable and relevant experiences that engage users effectively.
Context: Context refers to the circumstances or factors that surround a particular event, situation, or piece of information, influencing how it is understood and interpreted. In design and communication, context is essential for creating meaningful alt text and captions, as it helps provide clarity and relevance to the audience, enhancing accessibility and comprehension.
Deaf or hard of hearing users: Deaf or hard of hearing users are individuals who experience varying degrees of hearing loss, affecting their ability to perceive sounds in their environment. This group often relies on alternative communication methods, such as sign language, lip reading, and written text to engage with information. Accessibility features like alt text and captions are crucial for ensuring these users can fully participate in content and digital experiences.
Descriptive language: Descriptive language refers to the use of vivid and detailed words to paint a picture in the reader's mind, helping them visualize scenes, characters, and emotions. This type of language plays a crucial role in enhancing communication, especially in written formats, making content more engaging and accessible for various audiences. It serves to convey complex ideas and feelings clearly, often improving understanding and retention.
Educational videos: Educational videos are visual media designed to convey information, teach concepts, or enhance understanding on a specific subject. These videos often incorporate various elements like animations, interviews, and demonstrations to engage viewers and facilitate learning. They serve as valuable resources in both formal and informal educational settings, helping to cater to different learning styles.
Functionality: Functionality refers to the range of operations that can be performed by a system or product, particularly how effectively and efficiently it meets user needs. It encompasses features, capabilities, and the overall utility of a design, ensuring that users can accomplish their tasks seamlessly. In the context of visual content, such as images and videos, functionality plays a critical role in accessibility through alt text and captions, making sure that information is conveyed to all users, including those with disabilities.
Images: Images refer to visual representations or depictions that convey information, ideas, or emotions. They can include photographs, illustrations, graphics, and other visual elements that enhance understanding and engagement with content. Images play a crucial role in digital communication, as they can complement text and help in making complex ideas more accessible to a broader audience.
Live events: Live events refer to real-time occurrences or activities that engage an audience, typically through in-person or online participation. These events can include concerts, sports games, webinars, or conferences, and they often rely on elements such as alt text and captions to enhance accessibility for participants who may have disabilities or language barriers. Incorporating alt text and captions into live events ensures that all attendees can fully engage with the content being presented.
Screen Readers: Screen readers are software applications that convert digital text into synthesized speech or Braille, allowing visually impaired users to access and interact with digital content. These tools play a crucial role in making technology accessible, ensuring that individuals with visual impairments can navigate websites and applications effectively. Screen readers work by interpreting the information displayed on the screen and providing audio or tactile output, which is vital for inclusive design and creating a more equitable digital landscape.
User experience design: User experience design is the process of enhancing user satisfaction by improving the usability, accessibility, and pleasure provided in the interaction between the user and a product. This involves understanding users' needs, behaviors, and the context of their use to create intuitive interfaces that facilitate meaningful experiences. It connects to various elements like alt text and captions, which play a critical role in making content more accessible and ensuring that users can engage with the product effectively.
Videos: Videos are digital recordings that capture moving images and sound, often used to convey information, tell stories, or entertain. They can include various formats such as short clips, films, or live broadcasts and are frequently utilized in online content, presentations, and social media. With the rise of the internet, videos have become essential for communication and education, especially when combined with accessibility features like alt text and captions.
Visually impaired users: Visually impaired users are individuals who experience a partial or total inability to see, which can affect their interaction with visual content. This impairment can result from various conditions, such as blindness or low vision, and necessitates the use of assistive technologies or alternative formats to access information. Understanding how to accommodate visually impaired users is crucial for creating accessible digital content that ensures equal access to information.
WCAG Guidelines: The WCAG (Web Content Accessibility Guidelines) are a set of internationally recognized recommendations aimed at making web content more accessible to people with disabilities. These guidelines provide a framework for web designers and developers to create content that is perceivable, operable, understandable, and robust for all users, regardless of their abilities. Adhering to these guidelines not only ensures inclusivity but also improves overall user experience and usability across various platforms.