- Man pages: http://www.kernel.org/pub/software/scm/git/docs/
- Overview: http://www.kernel.org/pub/software/scm/git/docs/everyday.html
- User manual: http://www.kernel.org/pub/software/scm/git/docs/user-manual.html
- Documentation list on wiki: http://git.or.cz/gitwiki/GitDocumentation
- Wiki: http://git.or.cz/gitwiki
- Howtos: http://www.kernel.org/pub/software/scm/git/docs/howto-index.html
- Glossary: http://www.kernel.org/pub/software/scm/git/docs/glossary.html
- Third party tutorials and advocacy:
For more links, see "Git documentation".
I would rate the documentation as being on par with Subversion's (excellent) documentation, which is very fortunate considering Git's complexity and the learning curve necessary (primarily to unlearn patterns picked up from working with other version control systems and then relearn things "the Git way").
The mailing list often provides very interesting background information that goes into much greater depth than is possible with the end-user documentation.
Git is a excellent version control system and it was written by Linus Torvalds; these two factors make Git extremely attractive to Linux enthusiasts, already renowned for their enthusiasm. As a result Git boasts probably the single most active developer community among the open source version control systems, streets ahead of SVK (which is mostly developed and maintained by a single person) and possibly even more than Subversion (which numerically speaking probably has a significantly higher number of users but not developers).
Git is being constantly updated and improved. It very rapidly achieved a high level of sophistication, feature-completeness, and it's proved its mettle managing large projects such as the Linux kernel itself. Despite already being a very capable and efficient tool, improvement is rapid and ongoing.
Content-tracking rather than file-tracking
Whereas every other version control system in the world tracks file history (when lines were added to a file, when lines were removed, when a file was renamed, added or deleted etc) Git doesn't explicitly track this information in any way at all. It instead tracks content within a repository. By walking the repository history Git can reconstruct what happened to a particular file, but this is an extrapolation from the data rather than something explicitly encoded.
This is a radical departure that means that when you do something like cutting a method from one file and pasting it into another then the history of the method goes along with it (think
svn blame). This is explained by Linus Torvalds in this post; see also this separate post on tracking renames.
First off, let's just posit that "files" do not matter. The only thing that matters is how "content" moved in the tree. Ok? If I copy a function from one file to another, the perfect SCM will notice that, and show it as a diff that removes it from one file and adds it to another, and is _still_ able to track authorship past the move.
While Git shares many or all of the advantages of SVK there is one area in which it excels: performance. Whereas SVK is written in Perl, Git is largely written in C; specifically, the lower level "plumbing" is written in C and some of the higher-level "porcelain" is written higher-level (but slower) scripting languages. The "heavy lifting", however, is all done in C and is correspondingly fast. There is a Google "Summer of Code" project fro replacing some of the core scripts with C versions (see http://code.google.com/soc/2007/git/appinfo.html?csaid=BB370B5D857FA7A).
Low barrier to participation
It is incredibly easy to start managing code with Git. Unlike Subversion there is no need to set up a repository on a (possibly remote) server before starting to work. Git is even simpler than SVK, because what would normally be considered a "working copy" actually becomes a (distributed) repository itself, containing both the "working copy" and all of the history of the repository (this is different from SVK, where working copies are separate from repositories, which are typically mirrored under
Git makes branching and merging very cheap and easy operations, and (fortunately) comes with the visualization tools necessary to understand and manage projects with many branches and merges. gitk is a simple GUI repository browser and QGit is somewhat more advanced one; both permit visualization of repository history (including branches, merges, tree state, diffs). I am not aware of any tools for Subversion or SVK, for example, which rival the sophistication of these tools (especially QGit).