What are the functions of the horizontal tail in aircraft stability and control?

The horizontal tail serves multiple functions: Longitudinal stability (tail provides restoring pitching moment when angle of attack changes), Trim (tail generates force to balance wing-body pitching moment at various flight conditions), and Pitch control (elevator deflection creates pitching moment for maneuvering). The tail can be a fixed stabilizer with hinged elevator, or an all-moving (flying) tail for greater control authority. Tail sizing considers stability requirements, trim drag minimization, and control power for rotation and recovery from stall. T-tails move the horizontal tail out of wing wake but have deep stall concerns.