So glad you asked!
"Parts" work is a type of "shadow" work, and a way to better understand how and why we find ourselves in conflict with some people, but maybe not so with others. This psychology-backed, research-based approach (that I learned from the PAIRS relationship trainings!) posits that we all have different "parts" within us - a cast of characters, if you will (or think Joy, Sadness, etc. à la Disney's Inside Out).
Some of these characters show up when we're at work, with friends and family, and with our partner. We all have more protective and defensive parts, as well as more vulnerable, connective parts. The goal in getting to know our "parts" and our partner's "parts" is to better understand why we do the things we do when interacting with our partners - and to better understand why our partner does the things they do when interacting with us, too!
"Parts" work also allows each of us a bit of objectivity. By being able to "see" the patterns we play out in relationship by identifying which "parts" of us show up in conflict, we can then understand not just how and why it happens - but how to resolve it more easily and quickly next time.
It's a fun and friendly way to get to know some of the "darker" parts of us that make us beautifully human and who we are. Fans of the creative and scientific alike will love this approach to relating!