The following list is just a sample of some useful modules. More modules are added by various people on a constant basis. You can check the latest modules and download them from the Drupal contributed modules project section.
NOTE: Not all contributed modules are listed here, and some of these docs are not updated to the most current module version. Please help by contributing documentation for those are not updated and updating those are which are not mentioned in this document. When possible work with the module contributor to making sure accuracy.
NOTE: Most module documentation has been moved to the relevant guide and section. Many contributed modules also are documented in the Building the site functionality handbook section. For example, documentation on image handling modules is in the Image Handling section of Working with Media and Files in this guide.