What is it?
A file system is a component of an operating system that is used to control how data is stored and accessed. Data is grouped in discrete storage units called files. This data may not be stored contiguously in storage but it is the OSs role to display a file in its full form. Important features of file systems include:
Filenames are used to identify a file stored on a file system. The OS may treat files as case sensitive but generally aren’t. Special characters in file names are generally discouraged if allowed at all, as the functionality of some tools may not work with special characters.
Directories, also known as folders, is a structure that contains references to other computer files or possibly other directories. They are used to group related files or directories together. As such, they work in a hierarchical manner, meaning that each directory may hold files or sub-directories that each have their own files.
File systems are used to manage the space on secondary storage. It keeps track of the memory blocks that are taken by files or are free to be written to. When a file is deleted, its memory locations are added to a list of free spaces. This means that the file still exists until the OS writes new contents to that file.