Turn signal blinks for a short while then stops

When I push my turn signal lever, the lights come on and sometimes, it blinks for a few seconds and then stops or some other times, the lights come on, but they don't blink at all.
I suspect it could be the turn signal relay, but I have seen other people say it's the flasher. Can you tell me the difference? Also please let me know where to find the relay or the flasher in the car. Thank you in advance.