Once the most common Linux file systems is the ext2 (the second extended) file system. A
disadvantage is that file system checks on ext2 can take a long time.
ext2 was being replaced by ext3 on most Linux machines. They are essentially the same,
except for the journaling which is only present in ext3.
Journaling means that changes are first written to a journal on the disk. The journal is
flushed regularly, writing the changes in the file system. Journaling keeps the file system
in a consistent state, so you don't need a file system check after an unclean shutdown or
power failure.