What are some common criteria used to classify computer files?

Computer files are commonly classified by their file type, which describes the kind of content the file holds and how the operating system should open and handle it, for example a document, an image, an audio recording, or a program. This classification is closely tied to the file's content, since the type of content stored, such as text, pictures, or sound, determines what the file actually is and which application can correctly open it. File extensions, such as .docx, .jpg, or .mp3, are the visible signal of this classification.

Operating system compatibility and hardware requirements describe whether a program will run on a given machine, not a way of classifying an individual file's own content. File size and creation date are properties recorded about a file, but on their own they say nothing about what kind of file it is, so classifying by only those two properties is incomplete. Font style and colour describe formatting choices inside a document and are not a criterion used to classify the file itself.

Examination reminder: file classification centres on what the file actually contains and how that content is structured, which is why file type and content are the standard criteria.