What is SQL Server deadlock graph and how do you analyze it?

A deadlock graph shows cyclic resource waits between processes and helps identify victim selection.

When a deadlock occurs, SQL Server selects a victim transaction and captures a deadlock graph in XML format. It includes processes, resources, lock modes, and cycle detection. Analysts use Extended Events or system_health session to retrieve it. The graph reveals root cause like missing indexes, inconsistent access order, or long transactions.