What is a file, really?

Forget what “file” sounds like — paper, manila folders, an office. On a computer, a file is much simpler than that:

A file is a chunk of data with a name on it.

The chunk could be the pixels of a photo, the bytes of a song, the words of an essay, or the instructions that make Spotify run. None of that matters to your computer. What matters is:

• It has a name (so you can find it again).
• It has contents (the actual bytes).
• It has a size (how many bytes that is).
• It has a location (which folder it lives in — we’ll get to that next).

Take any of those away and you don’t have a file anymore.

Files are dormant

This is the part that trips people up, especially if you’ve spent years double-clicking icons.

A file, on its own, does nothing. A photo isn’t being looked at. A song isn’t playing. A document isn’t open. A file just sits on the disk, waiting. Something else has to come along and read it.

When you double-click a photo, your computer opens an app (Preview, Photos, whatever) and that app reads the file and shows it to you. The file didn’t “do” anything. The app did.

Hold onto this. Half of what’s confusing about computers gets less confusing once you stop thinking of files as active.

What’s not a file?

Almost everything you can name is a file. Your photos, your apps, your music, your text messages (yes, even those — stored in a file somewhere), your saved games. A few things aren’t:

• Folders — they hold files. They’re more like labels. Next lesson.
• Windows on your screen — those are running apps, not files. The app that opened them is a file.
• The internet — pages you visit live on other people’s computers as files.

What’s next

A file has to live somewhere. That somewhere is a folder. That’s the next piece.