Puppet Forge is a website that is used to share the Puppet modules. The website is https://forge.puppetlabs.com. There is good documentation of Puppet Forge that explains how to write your own modules on Puppet docs. You can find the details at http://docs.puppetlabs.com/forge/. There are lot of modules written to solve the daily administration and configuration problems. Before starting to write a specific module for yourself, it is a good place to check whether your needs are already covered by a module in Puppet Forge.
There are different levels of certification for modules in Puppet Forge. The best level is the Supported level. Supported means that:
The module is tested by Puppet Enterprise
It is subject to the Puppet Enterprise support
It will be maintained over the life cycle of the module with bug and security patches
It will be tested and ensured that it is compatible with multiple platforms