The ext2, ext3 and ext4 filesystems are some of the most known and used filesystems specifically designed for Linux. The first one, ext2 (second extended filesystems) is, as its name suggests, the older of the three. It has no journal feature, which is the biggest advantage of its successor over him: ext3. Released in 2008, ext4 is the more recent, and currently the default filesystem on many Linux distributions.
This is a companion discussion topic for the original entry at https://linuxconfig.org/how-to-tune-linux-extended-ext-filesystems-using-dumpe2fs-and-tune2fs