You have heard the term ‘parameter sniffing’, but you’re always a little bit fuzzy on the details. Is this a bug in SQL Server? Could it be happening to you? This video explains the truth about this complex and often confusing feature in SQL Server.
Video source and scripts: http://www.brentozar.com/archive/2013/11/why-parameter-sniffing-can-slow-down-queries-video/