The World-Wide Web, for apps -- Other candidates -- Content-addressable blob stores for persistent, self-certifying trees -- Distributed hash tables -- Persistent data structures -- Pub-sub -- Rolling hashes, or "the rsync algorithm" -- Backtracking or nondeterminism -- Memoization -- Monads -- Constraint solvers and logic programming (like SQL, but more so) -- Array languages like APL -- Probabilistic computing -- Incremental or self-adjusting computation -- Fully homomorphic encryption -- Convergent replicated data types -- AI optimization algorithms -- Graph search algorithms -- Particle filters -- Transparent persistence, or single-level store -- Ropes -- Snapshots of state, ephemeral and durable -- Virtual machines -- Automatic dependency tracking and deterministic rebuilding -- Prefix sum -- PID control -- String similarity -- Suffix arrays -- Formal methods Hash tables, expandable arrays, and sorting Transactions and transactional stores for concurrency Automatic differentiation Bitcoin Deep neural networks Conservative approximation Closures and Continuations Collaboration facilities Succinct data structures Interval arithmetic Lempel-Ziv compression: an update Gossip Algebraic incremental updates Compile-time instrumentation and object-code instrumentation