TitForTat can be understand as the biblical "eye for eye, tooth for tooth", but in this context this is not very interesting.
TitForTat is also a well-known simple and successful interaction game strategy:
This strategy is quick to forgive temporary destructive behaviour, to get back to collaboration. (ForgiveAndForget)
It shows predictable behaviour, that can't be exploited.
Maybe we need a TrustRoadMap.
Follow those who follow you — Automate! Unfollow those who unfollow you — Automate!
Problem: you are in an ambivalent cooperative situation. Your partner shows collaboration but also exploits you, in a maybe complex situation or history.
Solution: Don't think too much about the past, the future counts. Look at the immediate past and act accordingly. This is a simplification of the decision situation primarily. It allows you to act on a sound principle, if you want to.
Comments: If you change you mode of cooperation, communicate why you do this. The strategy won't work, if it is not understood by your partners, and they are used to exploit you.
TitForTat is definitely related to IteratedPrisonersDilemma by way of the work of RobertAxelrod? http://www-personal.umich.edu/~axe/ discussed in Axelrod's work Evolution of Cooperation http://cooperationcommons.com/node/398
That being said, I agree with Helmut that TitForTat should have it's own page, as IteratedPrisonersDilemma is not 1 to 1 equal to TitForTat, but rather, is a *strategy for "winning" IPD* according to Axelrod