This document provides an overview of transactional analysis (TA), a model developed by Eric Berne for understanding human interaction and communication. [1] TA posits that people have three ego states - Parent, Adult, and Child - and that interactions, or "transactions", between two people involve messages moving between their different ego states. [2] Transactions can be complementary, crossed, or ulterior. TA is used for behavioral, social, historical, and phenomenological diagnosis and has applications in organizational development to improve communication, relationships, and personal growth.