Camn any bro here enlighten me what exactly is karma?

issit like a vice verse which someone do something bad ending up with good karma.. yes i know my practice is wrong . which budistism is something that when u do a good deed and don't request for anything inreturn, but why am I always see people who don't pratice good habit in Goo deed always get the good stuff ? while the Good one that practice good habit usually is the one left out ? seriously I am lost . before posting here I did a survey with some social network and real life friend , which most of them don't really believe in karma . so I wonder is there such thing as karma or just simply lies.