The document discusses interaction design patterns, which are recurrent structures that afford specific interactions. Patterns help users transfer knowledge between applications, make interfaces predictable, and enable communication in design teams. The author advocates a pattern-based design process that involves identifying patterns, selecting patterns, articulating patterns into a coherent whole, testing patterns with users, and continually learning from patterns. Exercises are provided to generate a startup concept using pattern cards and design a website interface composed of interaction design patterns.