What are the Medical-Vocational Guidelines, or "Grids"?

The “Grids” are formally known as Medical-Vocational Guidelines and can be found here. DDS evaluates an applicant using these guidelines only at Step 5, so if the applicant meets a listing at Step 3, the Medical-Vocational guidelines will not be used. 

The guidelines reflect the analysis of the various vocational factors (i.e., age, education, and work experience) in combination with the individual's residual functional capacity (used to determine his or her maximum sustained work capability for sedentary, light, medium, heavy, or very heavy work) in evaluating the individual's ability to engage in substantial gainful activity in other than his or her vocationally relevant past work.