ALTAIR (ALTtitude conjugate Adaptive optics for the InfraRed) is the facility natural/laser guide star adaptive optics system of the Gemini North telescope. It can feed a corrected beam to Gemini instruments NIRI and NIFS. Deploying ALTAIR is "transparent" for the science instrument, as it reproduces the telescope focal ratio (f/16), pupil size and pupil position. ALTAIR is usable in the 1 - 2.5 micron range, with best results achieved in the H and K bands. L- and M-band performance is poor because of the low (~15%) transmittance of the ALTAIR optics in those bands and the greatly increased thermal background.