Coating technology for carbon-carbon has been driven primarily by the aerospace and defense industries, in applications where the composite is exposed to high-temperature oxidizing environments. The most notable application of coated carbon-carbon is for the nose cap and wing leading edges of the Shuttle Orbiter vehicle. This article details the fundamentals of protecting carbon-carbon composites. It explains various coating deposition techniques: pack cementation, chemical vapor deposition, and slurry coatings. The article discusses typical coating architectures in accordance with the process used to deposit the primary oxygen barrier. It also provides information on the practical limitations of coatings for the composites.