What is Come ?
Come is (verb) 1. to move to or towards this place Come and see us when you’re in London. The doctor came to see him yesterday. Some of the children come to school on foot. Don’t make any noise – I can hear someone coming. Come up to my room and we’ll talk about the problem. 2. to happen How did the door come to be open? how come? why?, how? (informal.) How come the front door was unlocked? 3. to occur P comes before Q. What comes after R in the alphabet? What comes after the news on TV? (NOTE: coming – came – has come)
source: Easier English, Student Dictionary Upper Intermediate Level