Sour beer is, well, sour. Usually 'spontaneously fermented', sometimes kettle sour (Goze!). Goze is very popular now. A little salty and sour, light and refreshing. But I love the 'lambic' style that is spontaneously fermented. usually a blend of oak-barrels aged up to 3 years, dry, very complex and 'funky'. Sooooooo good, but oh boy does it wreck me the next day!