The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is a stadium-sized facility that, when completed in 2008, will contain a 192-beam, 1.8-megajoule, 500-terawatt, ultraviolet laser system together with a 10-m-diam target chamber and room for 100 diagnostics. NIF is the world's largest and most energetic laser experimental system and will provide a scientific center to study inertial confinement fusion and matter at extreme energy densities and pressures. NIF's energetic laser beams will compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to initiate the fusion reactions. Other NIF experiments will study physical processes at temperatures approaching 108 K and 1011 bar, conditions that exist naturally only in the interior of stars and planets. NIF has completed the first phases of its laser commissioning program. The first four beams of NIF have generated 106 kJ in 23-ns pulses of infrared light and over 16 kJ in 3.5-ns pulses at the third harmonic (351 nm). NIF's target experimental systems are being commissioned and experiments have begun. This work provides a detailed look at the NIF laser systems, laser and optical performance, and results from recent laser commissioning shots. We follow this with a discussion of NIF's high-energy-density and inertial fusion experimental capabilities, the first experiments on NIF, and plans for future capabilities of this unique facility.