It is a perfect introduction to behavioural product psychology as Nir Eyar shares his insights on psychology, business, and tech using a four-fold model, which explains how to create habit-forming products. An external trigger \u2014 like an email or notification or ad that brings the user back. Our emotions often drive our behaviour, and each emotion is mapped to a set of products we could use to \u201cscratch the itch\u201d, as Eyar calls it, of whatever we are feeling. It\u2019s really a must-read if you want to understand the psychology behind what drives our behaviour in a world where there are so many services competing for our attention.<\/p>\n