In Linux, a file system is a method for storing and organizing data on a computer. The Linux file system is designed to provide a hierarchical and organized structure for files and directories, making it easy to navigate and manage data on the system. The Linux file system unifies all physical hard drives and partitions into a single directory structure, starting at the top with the root (/) directory. The Linux file system has a hierarchical file structure, with a root directory and its subdirectories. The topmost directory is called the root (/) directory, and all other directories in Linux can be accessed from it. Linux supports almost 100 types of file systems, including some very old ones as well as some of the newest. Each of these file system types uses its own metadata structures to define how the data is stored and accessed. Some of the most commonly used file systems in Linux include EXT4, XFS, BTRFS, JFS, and ZFS. The term "to mount" a file system in Linux refers to the process of logically attaching a file system to a specified mount point on a Linux file system.