An AMP file (or Alfresco Module Package) is a collection of code, XML, images, CSS, etc. that collectively extend the functionality or data provided by the standard Alfresco repository.

An AMP file can contain as little as a set of custom templates or a new category. It can contain a custom model and associated UI customisations. It could contain a complete new set of functionality, for example records management.

As a general rule of thumb, anything that is considered to be an ‘installable’ extension to the Alfresco repository should be called a module and packaged as an AMP file.

AMP files can be installed into the Alfresco WAR using the Module Management Tool. An AMP file has a standard format described below which can be customised if required.

AMP files can now also be created via Apache Maven 2 archetypes and have their lifecycle and deployment into Alfresco managed by the Maven Alfresco AMP archetype. For a full description of Maven AMPs Alfresco support see here

Once the contents of the AMP file has been mapped into an Alfresco WAR using the Module Management Tool, the WAR can be deployed to the application server. When the repository is next started, the installed module configuration will be detected, and the repository will be bootstrapped to include the new module functionality and data.

Please refer to http://wiki.alfresco.com/wiki/AMP_Files for more info.