This document discusses biosimilars, which are biologic drugs that are similar but not identical to already approved biologic drugs (reference biologics). It provides background on biologics and biosimilars, including that biosimilars take longer and cost less to develop than original biologics. Several regulatory issues for biosimilars are also discussed, such as naming, substitution, approval of indications, and reimbursement. The US recently approved its first biosimilar, but still lags behind Europe in approving and using biosimilars.