PHP modules are extensions mostly written in C language. They can be compiled with PHP to enable static loading (as part of the binary file) or dynamic loading (with the php.ini directive: extension=modulename.so).
There are different types of modules – core extensions, bundled extensions that are still part of the PHP package and fully external extensions. The last ones are not part of the PHP core and not included in the package.
Shared hosting and Managed VPS servers by SuperHosting.BG support a vast number of PHP modules. Some of them are static and do not require activation to start being used. To enable PHP dynamically loading modules, you need to access cPanel » PHP Manager by SuperHosting » PHP modules management.
The phpinfo function allows you to view all statically loading modules. All content from the Configure Command field, starting with –enable or –with is a compiled PHP module.
The dynamically loading modules (modulename.so) can be viewed in cPanel » PHP Manager by SuperHosting » PHP modules management.
There is a repository for PHP extensions called PECL (PHP Extension Community Library). Other PHP extensions exist, as they are different from PECL, but PECL is the official repository for the most popular and widely used PHP extensions.
Help documentation for PECL extensions is available on the official PHP website.
Some PECL extensions have been integrated in the PHP core, i.e. filter (pecl/php.net), json (pecl/php.net), xmlreader (pecl/php.net) and many others.
PECL modules differ from PEAR packages, although they use the same distribution system (PEAR).