Definition of hunting
Chasing is the act of running cards. The majority of the time in Hold'em, the flops will give us draws, not solid hands. For example, if a player has 8-9 on 6-7-2 and calls the bet on the flop, he is said to be chasing a straight. Any hand can be chased. If you have A2 in spades on 5-6-K with two spades, you are chasing the flush.
You have to know when to hunt and when not to hunt
Chasing hands in poker is normal, but you have to know when to do it and when not to do it. The best indicator of when to chase is the size of our opponent's bet. First, it is important to always keep in mind how often we will hit our draw. Then, we will relate this probability to the size of the bet. If we are on the turn with a flush draw, we know roughly that we will hit our flush on the river 20% of the time. If the pot is €10 and our opponent bets €10 on the turn, we will have to pay €10 to win €20 knowing that 4 times out of 5 we will hit nothing. So we don't have the odds to chase.