When I play recreational football, I pursue my man or a player a lot. Sometimes, out of nowhere, their back foot clip my thigh while running and they trip. It looks bad from far away and a foul is taken. I haven't done much besides running behind them or a bit on the side.
In another case, I was standing still and when the player twist and run, the same thing happen.
Is an unintentional clipping from behind considered as a foul in football?