A cat will often rub there face and body against an object or person in order to mark it with their scent. However, this can also be a greeting or a sign of affection. A friendly greeting between cats is the touching of noses, and this is often followed by the cat rubbing their cheek against your face. If you are standing up, you’re cat may rear up on his hind legs in order to have his face stroked. It is thought that this is because your face is too far away for them to rub against it in greeting and so they are helpfully lessening the distance.
Rubbing their bodies against your legs is also a good way of reminding you how lovely and affectionate they are when they want to be fed! This behaviour can, at times, be a little trying and they are also rather good at tripping you up by trying to run between your legs, but try not to be too angry as it is meant with affection.