File
also: files
A single named document stored on a computer. A project is made of many files, each holding part of the code, a picture, or some settings.
A named unit of stored data on disk. In a software project, files hold source code, settings, images and other assets. The ending of the name, such as .js or .py, usually signals what kind of content is inside.
A file is one document in a filing cabinet. It has a name on its tab and holds one specific thing.
Agents report their work file by file: "I edited three files." Knowing which files changed helps you judge how big a change was, and where to look if something breaks.
I updated 4 files: the signup page, the email template, the settings file, and one test. No other files were touched.
Only change the file that controls the menu page. Tell me first if you think another file needs to change too.
Thinking the ending of a file name, like .js or .css, is decoration. It tells the computer and your agent what kind of content the file holds.