The official Git SCM project provides official builds of the Windows command-line Git client as a free download. If you are using Windows then this is the recommended download for all Git users.
Cygwin is a port of many popular Linux/Unix tools to the Windows platform. Users familiar with Linux often install Cygwin to use familiar command-line tools under Windows. The Git command-line client is also included in Cygwin. To get started, download Setup.exe from the Cygwin homepage, and make sure to select the ‘git’ package. Previous command-line or Linux/Unix experience is recommended.
TortoiseGit is a Windows shell extension that integrates Git with the regular Windows interface. It adds new icons to Windows Explorer that identify which files have been checked out or modified etc. A right-click menu also provides access to all the usual Git commands, such as checkout, update and commit, as well as a powerful repository browser.
Visual Studio is the official Microsoft IDE on the Windows platform. Several different editions of Visual Studio are available, including the free Visual Studio Express edition.
Since the release of Visual Studio 2012 Update 2, Microsoft has released and maintained its own official Team Explorer extension for Git. This extension enables integration with local Git repositories and provides tools to work with remote repositories.
Eclipse is a popular open-source IDE developed in Java that supports a wide variety of runtime platforms, languages and environments. It is renowned for being extremely extensible and having a large variety of plug-ins available.
EGit is an Eclipse Team Provider plug-in for Eclipse IDE that provides seamless Git integration. EGit is implemented on top of JGit, the Java implementation of Git, and contains most of the functionality required to work with any Git repository.