Lightning Design Patterns discusses common problems when transitioning from Salesforce Classic to Lightning Experience and provides 3 design patterns to address these problems: (1) App All The Things, which treats every page as an app that can be built with drag-and-drop tools; (2) Accelerate with Actions, which uses global and quick actions to create/update related records faster; and (3) Context is Everything, which supports building components that are aware of the user, device, location, and environment context. The document provides resources for learning more about each design pattern on Trailhead.