Exam DEV-501 topic 1 question 3 discussion

A link that executes an action defined by a controller, and then either refreshes the current page, or navigates to a different page based on the PageReference variable that is returned by the action. An <apex:commandLink> component must always be a child of an <apex:form> component.
To add request parameters to an <apex:commandLink>, use nested <apex:param> components.