Surf is a user interface development framework that is used for implementing Share Web Scripts, pages and Dashlets This framework was originally developed by Alfresco, then donated to the Spring Source foundation, and finally brought back into Alfresco.
Surf is built on top of the Spring Web MVC technology, which uses the Spring Framework, and it provides a way of breaking a HTML page into reusable component parts.
More about Surf: https://community.alfresco.com/docs/DOC-5932-spring-surf