Store procedure is a compiled object that contain multiple  sql statement and it is fast in the  mater of execution .

An SQL STATEMENT can be executed from within code in a .Net application or this SQL STATEMENT can be packaged into a database and kept / stored there hence becoming a stored procedure.

Use of stored procedures increase the performance of a .net data driven application . Every time an SQL STATEMENT IS executed from a .net application , the statement is parsed,optimized and compiled by  SQL SERVER  whereas a stored procedure is parsed , compiled and optimised only one time . Its also better to use stored procedures as its more secure coding practice