What is a file? What is the difference between files and folders? give examples of file extensions?

Usually a file is understood as a piece of memory on a storage medium that has a name. But a file can be a lot more. For example, a file can be a printer, adding information to which we actually send it to print. For the convenience of users, hierarchical file storage is usually used, using folders for this. In fact, a folder is also files, but they cannot store ordinary information, but they contain information where you can find files and folders located in this folder.