When you start the Taverna Workbench, it automatically finds and loads the URLs of a default set of services that are commonly used (currently these services are mainly from the Life Sciences domain). You can search this default list by typing keywords into the Filter box at the top of the Service Panel in the Taverna Workbench 2.x.

If you do not find anything suitable or if you need to know more about a service and how it works, you can search the BioCatalogue either on the website or using the BioCatalogue integration built into Taverna 2.