When you win a pot using a hand that was supposed to have a fold for bet, there is a back into in force. As an example, two poker players who want to play draw poker agree to enter a pot. If the two of them draw to flushes and thereafter miss, then check after they make the draw; the one who has the ace-high backs into winning that pot as opposed to the one who had a king-high draw only.
Another good example of a back into is when a poker player begins a hand using 3 of the same type of car. However, if the poker player does a flush that is a runner-runner during the course of play, it means the flush is a "back into" type. When a player has a hand that is different from the hand that was first drawn to, the player is said to back into the hand. If for example, the 1st 4 cards in a hand of a 7-Card Stud are AA44 and a flush is made, the player will be backed into it.