The Linux kernel supports various filesystems. We'll explain ext2, ext3, ReiserFS, XFS and JFS as those filesystems are most commonly used on Linux systems.

ext2

ext2 is the tried and true Linux filesystem but doesn't have metadata journaling, which means that routine ext2 filesystem checks at startup time can be quite time-consuming. There is now quite a selection of newer-generation journaled filesystems that can be checked for consistency very quickly and are thus generally preferred over their non-journaled counterparts. Journaled filesystems prevent long delays when you boot your system and your filesystem happens to be in an inconsistent state.

ext3

ext3 is the journaled version of the ext2 filesystem, providing metadata journaling for fast recovery in addition to other enhanced journaling modes like full data and ordered data journaling. ext3 is a very good and reliable filesystem. It has an additional hashed b-tree indexing option that enables high performance in almost all situations. In short, ext3 is an excellent filesystem.

ReiserFS

ReiserFS is a B*-tree based filesystem that has very good overall performance and greatly outperforms both ext2 and ext3 when dealing with small files (files less than 4k), often by a factor of 10x-15x. ReiserFS also scales extremely well and has metadata journaling. As of kernel 2.4.18+, ReiserFS is solid and usable as both general-purpose filesystem and for extreme cases such as the creation of large filesystems, the use of many small files, very large files and directories containing tens of thousands of files.

XFS

XFS is a filesystem with metadata journaling that is fully supported under Gentoo Linux's xfs-sources kernel. It comes with a robust feature-set and is optimized for scalability. We only recommend using this filesystem on Linux systems with high-end SCSI and/or fibre channel storage and a uninterruptible power supply. Because XFS aggressively caches in-transit data in RAM, improperly designed programs (those that don't take proper precautions when writing files to disk and there are quite a few of them) can lose a good deal of data if the system goes down unexpectedly.

JFS

JFS is IBM's high-performance journaling filesystem. It has recently become production-ready and there hasn't been a sufficient track record to comment positively nor negatively on its general stability at this point.

Source : Gentoo Handbook