ext - technical definition

(EXTended file system) The first file system developed exclusively for the Linux operating system. Introduced in 1992, it employed a virtual file system (VFS) interface: a generic API that allows different underlying architectures to be used. Volume size was increased to 2GB and file names to 255 characters, up from the previous 64MB and 14 character limitations of the Minix file system, the first file system used in Linux.

ext2 and ext3
In 1993, ext2 was introduced with enhancements, including the traditional Unix inode and features from the Unix File System (see UFS). Volume size was greatly increased to 32TB.

Introduced in 2001, the major enhancement to ext3 was three levels of journaling, the most robust of which duplicates the indexes and file contents in the journal before updating the actual file system (see journaling file system). See file system.