Shepard's is a citator.  It does not discuss law, or contain law.  It simply informs a researcher who has found a specific authority whether that authority has been cited in other materials, such as cases.  For instance, if State v. Joe, a case from 1980, is a case the researcher wants to rely on, the researcher would Shepardize that cite.   Shepard's would tell the researcher whether another case had cited Smith v. Joe, and even inform the researcher as to whether the later case overturned or otherwise affected Smith v. Joe.  Features:

• validates authority
• provides parallel cites
• can act as a case finder
• published by McGraw-Hill Publishing Company
• is considered non-authority

Shepard's Advance Sheets (left) are supplements to the hard bound Shepard's volumes.  They update the material within the bound volume (similar to a pocket part).  They are also called Cumulative Supplements.