Ingredients of a BPEL Process

I was going through BPEL concepts for learning OFM 11g and found the below information, where an explaination  was given for BPEL ingredients.
Below are the key Ingredients of a BPEL process.

1. A Service which needs to be called by the BPEL Process for performing a task
2. Various activities which are used to build up a BPEL Process for transformations and calculations etc.
3. Event handler or Fault handler for catching up exceptions.

Hope this information would be helpful for a starter in Oracle Fusion Middleware.