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: