Credit card churning is a method of opening and closing many credit cards to obtain points and miles to travel for free. If you want to grab lots of points and miles, having many credit cards can help create this path.
Travel hacking is the mode of gaining free or cheaper travel by earning points and miles through credit card sign-ups and bonuses.
Credit card churning opens up cards, hits the sign-up bonuses, and closes them. People will use credit card churning to earn air miles, travel rewards, or cashback.
Opening cards can allow you to increase your credit score. By paying off debt and being responsible, you can move your credit score from a fair score to a much higher one.
Now manufactured spending may sound a little illegal, but it is not. Manufactured spending is spending money to achieve card rewards from credit cards. You have to manufacture enough spending where you are not losing money.