first of all, I thought I get to ask my own questions
secondly, here's a wikipedia page about it: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwilivDDuJD7AhWkQEEAHbCPANEQFnoECA8QAQ&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FQuantum_field_theory&usg=AOvVaw20YoaOW2ff8pF8ls0FgBUG