The /etc/fstab is for setting up devices to mount at boot times. You can also set up mount options for each device. For more info on the /etc/fstab file, open a terminal and type: man fstab
I will advice NOT to make modifications to this file unless you know what you're doing
. I've seen posts in here where people edited the /etc/fstab file and the system did not boot up or devices didn't mount.