In colliding-beam facilities, the "final-focus system" must demagnify the b
eams to attain the very small spot sizes required at the interaction points
. The first final-focus system with local chromatic correction was develope
d for the Stanford Linear Collider, where very large demagnifications were
desired. This same conceptual design has been adopted by all of the future
linear collider designs as well as the Superconducting Super Collider, the
Stanford and KEK B Factories, and the proposed Muon Collider. In this paper
, the overall layout, physics constraints, and optimization techniques rele
vant to the design of final-focus systems for high-energy electron-positron
linear colliders are reviewed. Finally, advanced concepts to avoid some of
the limitations of these systems are discussed.