This paper discusses basic concepts of failure analysis and gives advice on how to interpret, e.g., function, failure, failure mode, failure cause, and failure effect, using a gate valve as an example. A general approach to identification and classification of functions and failure modes is presented and the various steps of failure analysis are discussed. The OREDA (Offshore Reliability Data) database is used to illustrate the interpretation of the basic concepts. Limitations in the use of OREDA are pointed out and proposals for enhancements of this database are given.