The Glasgow post-rock band Mogwai formed in 1995 when three friends, Stuart Braithwaite (vocals and guitar), Dominic Aitchison (guitar) and Martin Bulloch (drums), decided to make music together. With the later addition of Barry Burns (bass, keys and vocals) and John Cummings (guitar), the group became a five-piece trafficking in serious guitar rock. They’ve put out seven well-regarded studio albums, including last year’s Hardcore Will Never Die, but You Will. And although they had to postpone their previous two North American appearances, Mogwai (above, doing “San Pedro” on Late Night with Jimmy Fallon) is back, playing Webster Hall tomorrow and Friday. Do yourself a favor and go see them live.