An execution plan is the sequence of operations SQL Server query optimizer performs to run the statements. The SQL Server query optimizer creates an execution plan before it actually runs a query. As per Microsoft Book Online, “Execution plans graphically display the data retrieval methods chosen by the SQL Server query optimizer. Execution plans represent the execution costs for specific statements and queries in SQL Server using icons rather than the tabular representation produced by the SET SHOWPLAN_ALL or SET SHOWPLAN_TEXT statements”. This graphical approach is very useful that for understanding the performance characteristics of a query, and help you to determine whether the query is written as efficiently as possible. You can use the execution plan information to quickly troubleshoot poorly performing queries.