1Kinds of MemoryComputer memory is a hierarchy of places to keep state, each trading speed, capacity, cost, and durability in a different way.Frontier 2Storing & RetrievingEvery useful system needs to put information somewhere, find it again, and know whether what it found can be trusted.Frontier 3Forgetting on PurposeDeliberate forgetting turns deletion from a cleanup chore into a design discipline for safer, simpler systems.Frontier 4Memory as Attack SurfaceMemory is where software becomes real, which makes it both a workbench for programs and a target for attackers.Frontier