Apertures are openings in telescopes that allow light to enter. The size of the aperture is crucial as it determines the amount of light gathered and the resolution of the image.
Focal Length: The distance between the telescope's lens or mirror and its focal point, affecting magnification and field of view
Magnification: The process by which a telescope enlarges the appearance of an object, dependent on focal length and eyepiece
Field of View: The extent of the observable sky seen through a telescope at any given moment