In the very beginning of computer systems, the purpose of a File system[7] [9] [4] was to provide function which could locate where a given file is located on the disk (which sectors), delete a given file, create a new one and so on. In other words the file systems3 is a set of algorithm which can store the content of a file of any given size in the sectors the block device provides, be able to read the file again, delete it. All these features must be provided through the kernel API, so the kernel know how to use them.
This is still the main purpose of the file system, but as time pass the block devices have become cheaper, and computers more powerful, and this has made it possible to add more features to the file systems. File systems started include to include metadata about the individual files, such as creation timestamp, read/write timestamp, ACL4 and many more. An other new feature which was added is ``Hierarchical File System'', which provided support for nested folders (folders inside folders). Hierarchical file systems makes it possible for the users to create a directory structure which he/she find logical, and which can make it easier to find and arrange a lot of files.