String creep is a permanent stretching of the string. In other words, if your string is a 50 inch string, and yuo take it off and measure it and it is now 51 inches it has crept 1 inch.

Ways to tell:
1. Peep keeps rotating and will never settle in
2. Axle to axle has gone up
3. Brace heiht is shorter
4. Draw weight has gone up
5. Bow is no longer in time
or 6. take the string off and measure it