Many optional preface elements are possible. Only place elements at the start which are important to read before the main success scenario. Move extraneous “header” material to the end of the use case.
Primary Actor: The principal actor that calls upon system services to fulfill a goal.
This list is more important and practical than may appear at first glance. It suggests and bounds what the system must do. To quote:
The [system] operates a contract between stakeholders, with the use cases detailing the behavioral parts of that contract...The use case, as the contract for behavior, captures all and only the behaviors related to satisfying the stakeholders' ...