What types of relationships exist on a sequence diagram?

Sequence diagrams display interactions between objects or components over time. The main types of links:

• Message — the transfer of information or a method call from one object to another. It can be synchronous (waiting for a response) or asynchronous.
• Return Message — the response to a call, returned to the calling object.
• Create — a message that initiates the creation of a new object.
• Destroy — a message that terminates the object's lifecycle.

These links help visualize the order of calls and interactions within the system.