Terminology

791 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 areas791 Architecture Fundamentals38 Distributed Systems73 Data Architecture71 Cloud Architecture55 Networking51 API & Integration Architecture45 Reliability & Resilience40 Observability33 Performance & Capacity Engineering34 Security Architecture50 Cost Architecture & FinOps30 Business Architecture28 Architecture Communication27 Enterprise Architecture27 Legacy Modernization27 AI-Era Architecture34 Software Architecture & Engineering37 Architecture Patterns34 Architecture Decision-Making30 The Architect's Meta-Skills27

Kind Any concept292 practice240 pattern133 metric36 protocol32 tool32 case-study26

791 terms shown.

Term	Kind	Topic	What it is
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.
Thundering Herd	concept	Distributed Systems	A large number of clients acting simultaneously because they were synchronised by a shared event, producing a spike that the steady-state design never sized for.
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.
Time Travel Data Versioning, Snapshot Query	concept	Data Lakes & Lakehouses	Querying a table as it existed at a previous version or timestamp, made possible by keeping the metadata and files of prior commits.
Timeout Budget Deadline Propagation	pattern	Distributed Systems	Assigning a request an overall deadline at the edge and passing the remaining time down each hop, so no service works on something already out of time.
TLS Transport Layer Security, SSL	protocol	Networking	The protocol that gives a network connection encryption, integrity and server authentication, underneath HTTPS and most other secure transports.
TOGAF	practice	Enterprise Architecture	An enterprise architecture framework whose central element is the ADM, an iterative cycle from vision through business, data, application and technology architecture to implementation governance.
Toil	concept	Reliability Culture	Manual, repetitive, automatable operational work that scales with service growth and produces no lasting improvement.
Token Bucket	pattern	Rate Limiting	A rate-limiting algorithm holding a replenishing allowance of tokens, permitting controlled bursts while bounding the sustained rate.
Token Budget Enforcement	practice	AI Gateways	Limiting token consumption per user, tenant, feature or time window at a central point, so cost cannot run away unobserved.
Token Cost Attribution	practice	AI Cost Management	Assigning inference spend to features, tenants and users, so that cost can be managed by the people who influence it.
Token Introspection	protocol	OAuth 2.0 & OIDC	Asking the authorisation server whether a token is currently valid, rather than validating it locally from its signature.
Tokenisation	pattern	Security Architecture	Replacing a sensitive value with a non-sensitive surrogate, with the mapping held in one tightly-controlled vault.
Tool Calling Function Calling	pattern	AI-Era Architecture	Giving a model a set of typed function definitions it can request to invoke, with the application executing the call and returning the result.
Tool Schema Design	practice	Tool Calling	Defining the tools available to a model — names, descriptions, parameters and errors — in a way that makes correct selection likely.
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.
Trade-off Analysis	practice	Meta-Skills	Making the costs of an architectural choice explicit and comparable, rather than presenting a recommendation as if it were free.
Trade-off Framing	practice	Explaining Trade-offs	Presenting a decision as a choice between named costs rather than as a search for a best option, so the audience can exercise the judgement that is properly theirs.
Trade-off Surface	concept	Trade-off Analysis	The set of achievable combinations of competing qualities, on which improving one attribute necessarily costs another.
Traffic Splitting	pattern	Service Mesh Networking	Directing a defined percentage or subset of requests to a different version of a service, configured at the routing layer rather than in application code.
Trunk-Based Development	practice	Software Architecture	All developers integrating small changes into a single shared branch at least daily, with long-lived branches avoided entirely.
Trust Boundary Diagram	practice	Communicating Threat Models	A diagram marking where data crosses between zones of differing trust, which is the structure a threat model is built on and the form security findings are best communicated in.
Try-Confirm-Cancel TCC, Reservation Pattern	pattern	Distributed Transactions	A three-phase distributed transaction where each participant first reserves resources, and a coordinator then confirms or cancels all reservations.
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.
Two-Phase Commit 2PC, XA	protocol	Distributed Systems	A blocking protocol for atomic commit across several resources: a coordinator asks all participants to prepare, then tells them all to commit or abort.
Two-Phase Locking 2PL	protocol	Transactions & Isolation	The concurrency control protocol behind serializable isolation — acquire locks in a growing phase, release only in a shrinking phase, never interleaving the two.
Two-Pizza Team	concept	Business Architecture	Amazon's heuristic that a team should be small enough to be fed by two pizzas, and — the substantive part — should own its service end to end.
Two-Stage Retrieval	pattern	Reranking	Retrieving a broad candidate set cheaply and then reordering it with an expensive, more accurate model.
Two-Way Door	concept	Reversibility	A decision that can be undone cheaply, and which therefore warrants a fast decision by the people closest to the work rather than extensive analysis.
Uber's Domain-Oriented Microservice Architecture DOMA	case-study	Software Architecture	After growing to roughly 2,200 microservices, Uber grouped them into domains behind gateways with strict dependency layering, to recover the comprehensibility that fine-grained decomposition had cost.
Uber's H3 Spatial Index	case-study	Data Architecture	Uber indexes the world with hexagons rather than squares, because uniform neighbour distance makes supply, demand and pricing computations correct as well as fast.
Ubiquitous Language	practice	Domain-Driven Design	A shared vocabulary used identically by domain experts and in the code, so that translation between business and implementation is unnecessary.
Unit Economics	metric	Unit Economics	Infrastructure cost expressed per unit of business value delivered, which reveals efficiency trends that absolute spend cannot.
USE Method	practice	Observability	For every resource, track Utilisation, Saturation and Errors — the resource-centric complement to request-centric monitoring.
Utilisation and Queueing Delay	concept	Queueing Theory	The non-linear relationship by which waiting time grows as utilisation approaches one, explaining why systems degrade suddenly rather than gradually.
Utilisation Floor	metric	Rightsizing	The minimum utilisation a resource should sustain before it is considered over-provisioned, set with enough margin for failure and peak.
Utility Tree	practice	Quality Attributes	A structured decomposition of quality attributes into concrete, prioritised scenarios, used to focus architectural analysis on what actually matters.
Value Stream	concept	Business Architecture	The end-to-end sequence of activities that delivers a result to a customer, viewed across whatever departments and systems it happens to cross.
Vector Database	tool	AI-Era Architecture	A store optimised for approximate nearest-neighbour search over high-dimensional embeddings.
Vendor Lock-In	concept	Technical Constraints	The cost of switching away from a provider, treated as a quantity to be managed deliberately rather than a condition to be avoided absolutely.
Version Vector Vector Clock	concept	Clocks & Ordering	A per-replica counter set that lets a system tell whether one version causally descends from another or whether the two are genuinely concurrent.
View Staleness Window	concept	Materialized Views	The maximum age of data in a precomputed view, which must be an explicit, monitored contract rather than an incidental property.
Virtual Private Cloud VPC, VNet	concept	Networking	A logically isolated network inside a cloud provider, with an address range you control and explicit rules for what may enter and leave.
Visibility Timeout	concept	Messaging & Queues	The period after a consumer receives a message during which it is hidden from other consumers, before it becomes available again for redelivery.
VPC Peering	concept	VPC Design	A direct network connection between two VPCs, which is simple, cheap and non-transitive — the last property being the one that shapes topology.
VPN vs Dedicated Connection Direct Connect, ExpressRoute	concept	Private Connectivity	Two ways to link on-premises networks to cloud — an encrypted tunnel over the internet, or a private physical circuit.
Warm Pool	pattern	Autoscaling	Pre-initialised instances held in a stopped or standby state so that scaling out skips boot and application warm-up.
Watermark	concept	Streaming Data	A moving assertion that no events older than a given event-time will arrive, which is what allows an event-time window to be closed and emitted.
Web Application Firewall WAF	tool	Network Security	A filter in front of an application that inspects HTTP requests and blocks those matching known attack patterns — useful as a layer, dangerous as a substitute.
Webhook	pattern	API & Integration	An HTTP callback from a provider to a consumer-supplied URL when an event occurs, replacing polling with push.
Webhook Retry Policy	concept	Webhooks	The provider's schedule for re-attempting failed deliveries, and the contract the receiver must be built against.
Webhook Signature	practice	Webhooks	An HMAC over the raw request body using a shared secret, letting a receiver verify a webhook genuinely came from the provider.
WebSocket	protocol	Networking	A protocol that upgrades an HTTP connection into a persistent, full-duplex channel so the server can push to the client without polling.
WebSocket Backplane	pattern	WebSockets & Realtime	A shared publish/subscribe layer letting a message published on one server reach clients connected to a different server.
Weighted Decision Matrix	practice	Trade-off Analysis Methods	A scoring method that rates options against weighted criteria, used to expose disagreement about priorities rather than to produce an answer.
Weighted Shortest Job First	practice	Portfolio Prioritisation	Sequencing work by dividing the cost of delaying it by the effort to deliver it, which maximises value delivered per unit of time.
Well-Architected Review	practice	Cloud Architecture	A structured self-assessment of a workload against defined pillars — operational excellence, security, reliability, performance, cost, and sustainability.
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.
Wide-Column Store	tool	NoSQL Stores	A store organised as partitions of sorted rows, designed for very high write throughput and predictable single-partition reads at large scale.
Windowing	concept	Streaming Data	Grouping an unbounded stream into finite chunks so aggregation can produce results, defined over event time rather than arrival time.