The ext2 file system was a common file system for Linux systems. It has been supplanted for the most part by ext3 and ext4, which are backwards-compatible with it. It is still used on USB drives since it is not journaled, reducing the number of writes made to the drive (but thus increasing corruptibility).
The normal common file system is ext2 or 3.
Typically one uses an older file system to be compatible with older systems that do not support a newer (safer) version.
By default it should be using the ext3 file system, but you have a choice of several, including ext2, reiserfs, etc. Newer versions of Ubuntu tend to install as ext4 file systems, however if you've upgraded from an older version then you'll keep your original file system.
An ext2 file system can be created through a variety of methods. The crudest method, where the partition occupies an entire disk, can be done on most Linux distributions with the commandmkfs.ext2 /dev/hdaOther frontends, such as cfdisk or GPartEd, will allow you to more easily create partitions of different sizes on the disk.
Several, such as ext2/3/4, ReiserFS, btrfs, cramfs, romfs, SquashFS, and Xiafs.
Windows XP natively supports FAT12, FAT16, FAT32, and NTFS. Other file systems, such as HPFS, JFS, ext2/3, and ReiserFS can be supported through an IFS (Installable File System).
There are a couple different IFS (Installable File System) drivers that can be used to do this. Links to them are posted in the "Related links" section below.
ext4 supports a feature called 'journalling' which prevents filesystem corruption in the event of a power failure or system crash. When you are certain you don't need it, you can choose ext2. But for the vast majority of users, ext4 is the best option.
The Linux ext3 file system is the default system in many linux derivatives. It allows for journalling, which the ext2 system did not. It also allows in-situ upgrades without asking for a backup first.
You can set up file sharing between windows 7 and Linux mint 16 by simply installing the Ext2 Installable File System on windows which allow windows to read and write into the Linux file system.
ext2, ext3, ReiserFS, are some native file systems
There are programs you can download that will read Linux file systems. Common file systems are ext2 and ext3.