What are Apache contrib modules?

For most of the Apache project, there are contrib modu开发者_JAVA百科les. What is the significance of these contrib modules?

http://goo.gl/U3iA2

Typically they're modules submitted to the project by the community. Though they are hosted and made available by the project, they likely are not maintained by the project and probably not of the same robustness in terms of testing, code quality, and/or documentation of the main project. Doesn't mean they aren't useful, they're just likely not useful to everyone and made available to all basically on an "as is" basis.