What are the different types of carbon fiber and their applications?

Carbon fibers are classified by properties: Standard modulus (SM) - E ~230 GPa, UTS ~3500 MPa, most economical, general applications; Intermediate modulus (IM) - E ~290 GPa, higher strain capability, widely used in aerospace (T800, IM7); High modulus (HM) - E ~350-450 GPa, lower strain, used where stiffness is critical (spacecraft); Ultra-high modulus (UHM) - E >450 GPa, very brittle, specialized applications. Precursors: PAN-based (Polyacrylonitrile) - dominant for aerospace, best properties; Pitch-based - high modulus, better thermal conductivity. Formats: Tow (continuous filaments, 3K-24K filaments), Woven fabric (various weaves for drapability), and Prepreg (fiber pre-impregnated with resin). Selection: IM fibers (T800, IM7) most common for primary structure; SM for less critical parts; HM where deflection is limiting. Fiber selection significantly affects composite properties.