The collection of files and directories located on a computer's hard drive..
A directory structure contained within a disk drive or disk area. The total available disk space can be composed of one or more filesystems. A filesystem must be mounted before it can be accessed. To mount a filesystem, you must specify a directory to act as the mount point. Once mounted, any access to the mount point directory or its subdirectories will access the separate filesystem.
a data structure (sort of like an array) that contains a superblock, an inode list, and data blocks