Q:

Is there a GUI client for Git?

I am using git for version control of various projects.
Is there GUI software for navigating through commits and branches of a project and for retrieving versions in git projects?

A:

I guess you are looking for an easy to use front-end for git.
Take a look at "Graphical Interfaces" section of InterfacesFrontendsAndTools page on Git Wiki.  There the following have been mentioned:

gitk - graphical history browser, in Tcl/Tk, distributed with Git (usually in gitk package)
git gui - graphical commit tool, in Tcl/Tk, distributed with Git (usually in git-gui package)
QGit - uses Qt toolkit
Giggle - uses GTK+ toolkit
git-cola - uses PyQt4
gitg - GTK+/GNOME clone of GitX
tig - text mode interface for git, is GUI and pager, uses ncurses

Edit: These are the suggestions given in the other answers.

GitKraken
SmartGit
gitg
rabbitVCS

There are a couple of software which I personally find very easy to use.

Giggle: I personally use giggle  . It is simple and intuitive to use.

Cola Git GUI: I have not used Cola Git , but this does seem promising.

A:

Having tested all the above mentioned tools, I have settled with the following tools for managing my Git repositories:

SmartGit
RabbitVCS

SmartGit
SmartGit is an easy-to-use graphical user interface for Git with optimized work-flows. SmartGit supports all Git and Mercurial features needed for every-day work in software development projects:

Local working tree operations 
Status, diff, log
Push, pull, fetch (for all protocols)
Tag and branch management
Merge, cherry-pick, rebase, revert
Submodule support
Stash management
Remotes management

I has also an easy to use wizard to connect you to online repositories like GitHub and BitBucket

RabbitVCS
In contrast, RabbitVCS has a different approach from other tools. Rather than providing an external UI for your git repository, it integrates its self to Nautilus. In fact RabbitVCS is a set of graphical tools written to provide simple and straightforward access to the version control systems you use. 

A:

Yes; git has a gui you can run with the git gui command.
If that doesn't work, it means you need to install the GUI for git. You can do this by installing the git-gui  package. Or, even better, install the git-all  package.
sudo apt-get update && sudo apt-get install git-all

See man git-gui for details. Note that while the manpage is called git-gui, you run this as git gui.

