Terminology

384 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 areas384 Architecture Fundamentals16 Distributed Systems73 Data Architecture71 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 concept136 practice90 pattern81 case-study26 protocol19 tool19 metric13

13 terms shown.

Term	Kind	Topic	What it is
Cost per Request	metric	Cost & FinOps	The fully-loaded infrastructure cost of serving one request, and the unit that makes architectural cost decisions comparable.
DORA Metrics Four Key Metrics	metric	Software Architecture	Four measures of software delivery performance — deployment frequency, lead time for change, change failure rate, and time to restore service.
Error Budget	metric	Reliability & Resilience	The amount of unreliability an SLO permits, treated as a resource that feature velocity spends.
Golden Signals	metric	Observability	The four measurements that cover most of what matters for a request-driven service: latency, traffic, errors and saturation.
Index Selectivity	metric	Indexing	The fraction of rows a predicate eliminates — the property that determines whether an index is worth using at all.
Replication Lag	metric	Replication	How far behind a replica is, measured in time or in log position — the quantity that determines how stale a replica read can be.
RTO and RPO Recovery Time Objective, Recovery Point Objective	metric	Reliability & Resilience	How long recovery may take (RTO) and how much data may be lost (RPO), the two numbers that determine the cost of a resilience design.
Service Level Indicator SLI	metric	Reliability & Resilience	The actual measurement of a service's behaviour that an objective is set against — a ratio of good events to valid events.
Service Level Objective SLO	metric	Reliability & Resilience	An internal target for a service level indicator, set below the level at which users notice, and used to decide whether to ship or to stabilise.
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.
Time to Market	metric	Business Architecture	How long it takes to get a capability in front of customers — often the constraint that dominates every other architectural quality.
Total Cost of Ownership TCO	metric	Cost & FinOps	The full lifetime cost of a capability, including the people, operations, upgrades and exit that a licence comparison leaves out.