Physical versus Logical Files
Physical File: A collection of bytes stored on a disk or tape.
Logical File: A “Channel” (like a telephone line) that hides the details of the file’s location and physical format to the program.
When a program wants to use a particular file, “data”, the operating system must find the physical file called “data” and make the hookup by assigning a logical file to it. This logical file has a logical name which is what is used inside the program.