Terminology

342 terms, tools, patterns and metrics an architect is expected to use precisely. Each one gets a short explanation of what it is, and — where it matters — what it is commonly confused with. Search filters as you type; the column headers sort.

All areas342 Architecture Fundamentals16 Distributed Systems73 Data Architecture29 Cloud Architecture17 Networking13 API & Integration Architecture17 Reliability & Resilience16 Observability14 Performance & Capacity Engineering13 Security Architecture18 Cost Architecture & FinOps12 Business Architecture9 Architecture Communication8 Enterprise Architecture8 Legacy Modernization11 AI-Era Architecture15 Software Architecture & Engineering19 Architecture Patterns15 Architecture Decision-Making11 The Architect's Meta-Skills8

Kind Any concept119 practice84 pattern70 case-study26 protocol18 tool14 metric11

13 terms shown.

Term	Kind	Topic	What it is
Caching Strategy	pattern	Performance & Capacity	The chosen pattern for how a cache is populated, read and invalidated — cache-aside, read-through, write-through or write-behind.
Concurrency	concept	Performance & Capacity	The number of operations in progress at once — distinct from parallelism, which is how many are literally executing simultaneously.
Connection Pool	concept	Performance & Capacity	A fixed set of reusable database connections shared by an application's requests, and one of the most common hidden capacity ceilings.
Google Maps and Planetary-Scale Spatial Serving	case-study	Performance & Capacity	Map serving is fast because almost nothing is computed on request — the world is precomputed into a pyramid of tiles, and space is indexed onto a one-dimensional curve.
Hedged Request Request Hedging, Tied Request	pattern	Performance & Capacity	Sending a duplicate of a request to a second replica after a short delay and using whichever response returns first, to cut tail latency.
Horizontal vs Vertical Scaling Scale Out vs Scale Up	concept	Performance & Capacity	Adding more machines versus making one machine bigger — and the fact that vertical is underrated for stateful tiers.
Little's Law	concept	Performance & Capacity	In a stable system, the average number of items in it equals the arrival rate times the average time each spends in it — L = λW.
Little's Law Applied to Pools	practice	Connection Pooling	Using L = λW to size connection and thread pools from measured throughput and latency rather than from a default.
Load Testing	practice	Performance & Capacity	Driving a system with realistic traffic at a target volume to verify it meets its performance targets before real users do.
Tail Latency p99, p999	metric	Performance & Capacity	The latency experienced by the slowest small percentage of requests, which is what users and dependent services actually feel.
Throughput	metric	Performance & Capacity	The rate of work a system completes per unit of time — and a quantity that trades against latency rather than tracking it.
Twitter's Timeline Fan-Out	case-study	Performance & Capacity	Twitter precomputes each user's timeline at write time but handles very-high-follower accounts at read time, because neither strategy alone survives both ends of the distribution.
WhatsApp's Small-Team Scale	case-study	Performance & Capacity	WhatsApp served hundreds of millions of users with a few dozen engineers by matching one technology choice precisely to the workload and refusing to add anything else.