What is SQL Server execution plan XML structure and operator tree representation?

Execution plans are represented as XML trees of operators with cost, cardinality, and runtime attributes.

SQL Server execution plans are serialized as XML containing hierarchical operator trees. Each node represents an operator (scan, seek, join, sort). Attributes include estimated rows, actual rows, cost, and memory grant. The XML structure allows tools like SSMS to visualize execution flow and identify bottlenecks such as spills, scans, or bad cardinality estimates.