We talk about how files are named, how they are created and destroyed and viewed, showing some simple commands. Many people have an intuitive concept of a computer file from work on Macintoshes, IBMs or other micros. Just to review, a file is any collection of data that is stored in a permanent area in a computer system. Files model real-world entities like documents, forms, reports, memos, pictures, sound clips, video clips, and almost any other way of storing some information together.
Every operating system has some way of storing and accessing files.
Some operating systems distinguish one type of file from another. For example a database file is stored in a different way than an executable program. In order to be as simple and general as possible, UNIX makes no assumption about what is in a file, and so it says that any sequence of bytes is a file. The exact type of file that it is doesn't matter to UNIX, although the program that reads and interprets the file expects it to be a certain type. Files may be stored on long-term storage devices like hard or floppy disks, but they are organized in logical clusters called directories.