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The size refers to the dimensions, magnitude, or extent of something. In programming, it typically indicates the number of elements in a collection or container.
The length refers to the number of elements in an array or the size of a string. It represents the total count or quantity.
Capacity: Capacity denotes the maximum amount that a data structure can hold without needing to be resized.
Count: Count is often used synonymously with size and represents the total number of items in a collection.