The majority of modern Linux distributions default to the ext4 filesystem, just as previous Linux distributions defaulted to ext3, ext2, and—if you go back far enough—ext. If you're new to Linux—or to filesystems—you might wonder what ext4 brings to the table that ext3 didn't. You might also wonder whether ext4 is still in active development at all, given the flurries of news coverage of alternate filesystems such as btrfs, xfs, and zfs.