The /etc/fstab file contains static file system information. It normally contains an entry for each partition name or UUID that lists the mount point, filesystem type and mount options.

fstab is an abbreviation of file system table. This file, located in /etc, contains information about static (non variable) file systems. The file is used to find and mount these file systems, at boot or as directed.

The file contains a line for each file system (for example, a drive partition) that gives an identifier, either a label like /dev/sda1 or, better, a UUID, followed by the mount point such as / or /boot/efi or none for a swap partition, the file system type such as ext4, vfat, ntfs, and mount options such as errors=remount-ro, and two numbers, dump and pass

# <file system> <mount point>   <type>  <options>       <dump>  <pass>

Comprehensive information about and examples of fstab can be found in the Ubuntu help wiki fstab page