What is a subject matter expert?

The subject matter expert (SME) provides the knowledge and expertise in a specific subject, business area, or technical area for a project/program. 

How do I define who the subject matter experts should be?

SMEs are typically found among those who have been in their roles for a long enough period of time for their knowledge and skills to be “second nature”. A SME should know their job well enough that they rarely have to look up information and, if they do have to, they know exactly where to find the information.