Ext3, or Third Extended File System, is a journaling file system used in many Linux operating systems. It was developed as an improvement over its predecessor, Ext2, by adding a journaling feature that helps protect data integrity. This means that it keeps a log of changes before they are made, allowing for easier recovery in case of a system crash or power failure. One of the key advantages of Ext3 is its backward compatibility with Ext2, allowing users to easily upgrade without losing data. It supports large file sizes and volumes, making it suitable for various applications, from personal computers to servers.