A kerb is the raised stone edge between the road, where cars go, and the pavement, where people walk. You step up onto it when you leave the street; a badly parked car may have a wheel up on it. This spelling is British. In American English the same roadside edge is spelled curb. Though actually, British English still uses curb — with a u — as a verb meaning “hold something back” (curb your temper, curb spending). The stone at the side of the road is the one that took the kerb spelling. You may also meet kerb-crawling, a bleak, specific use: driving slowly along the kerb to look for a sex worker. In ordinary talk, though, kerb is just that little step of stone, and kerbstone is the block itself.