This document provides an overview of formal methods and sequential equivalence checking from the perspective of a user at IBM. It discusses trends in formal verification, why formal methods are preferable to simulation-based techniques, and describes the verification process for new and derivative chip designs. It provides definitions for key terms like equivalence checking, logic cones, and sequential behavior. It also discusses lessons learned from applying sequential equivalence checking to verify changes made in the design of the Xbox 360 processor and PowerPC 464 floating point unit.