Interactive Evolutionary Computation (IEC) allows users to play a role in evolutionary algorithms by evaluating solutions. There are two definitions of IEC - narrow, where the user acts as the fitness function, and broad, where the user controls the search. IEC began in the 1980s and grew popular in the early 1990s. While application-focused, researchers have identified issues with IEC like user fatigue and developed techniques like fitness prediction and clustering to address them. Overall, IEC is a young field that could benefit from more formalization and understanding of techniques to better assist users.