Terminology

2185 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 areas2185 Architecture Fundamentals77 Distributed Systems107 Data Architecture110 Cloud Architecture89 Networking88 API & Integration Architecture82 Reliability & Resilience75 Observability70 Performance & Capacity Engineering72 Security Architecture81 Cost Architecture & FinOps66 Business Architecture67 Architecture Communication67 Enterprise Architecture66 Legacy Modernization66 AI-Era Architecture69 Software Architecture & Engineering71 Architecture Patterns71 Architecture Decision-Making63 The Architect's Meta-Skills61 Delivery & Release Engineering66 Platform Engineering & Developer Experience70 Testing & Quality Architecture66 Data Platform Architecture64 Streaming & Real-Time Data69 Data Governance & Semantics69 Frontend & Experience Architecture66 Edge, Mobile & IoT68 Regulatory & Data Protection Architecture65 Assurance, Audit & Model Risk64

Kind Any concept785 practice729 pattern362 metric125 case-study77 tool62 protocol45

77 terms shown.

Term	Kind	Topic	What it is
Abstraction	concept	Architecture Fundamentals	Exposing what a component does while hiding how it does it, so callers depend on the contract rather than the mechanism.
Abstraction and Encapsulation	concept	Abstraction & Encapsulation	Hiding mechanism behind a contract so the mechanism can be replaced — and the discipline of not letting the mechanism leak through the contract.
Accidental vs Essential Complexity	concept	Architecture Fundamentals	Essential complexity comes from the problem and cannot be removed; accidental complexity comes from your solution and usually can.
Afferent and Efferent Coupling	metric	Coupling	The counts of components depending on a module and of components it depends upon, used together to identify which parts of a system are expensive to change.
Architect Archetypes	concept	Architecture Roles	The distinct scopes of architecture practice — enterprise, solution, domain and application — and the different skills and decision rights each carries.
Architect Coverage Ratio Architect to Team Ratio, Gatekeeper Ratio	metric	Architecture Roles	Teams served per architect before the role turns into a review queue, used to decide whether to hire reviewers or to remove the need for review.
Architectural Debt	concept	Evolutionary Architecture	Structural compromises that increase the cost of all future change, distinguished from code-level debt by being expensive and slow to repay.
Architectural Driver	concept	Architecture Fundamentals	The small subset of requirements and constraints that actually shape the structure of the system.
Architectural Drivers	practice	Architectural Drivers	The handful of requirements whose change would force the structure to change — the only ones worth designing against.
Architecturally Significant Requirement ASR	practice	Architectural Drivers	The small subset of requirements whose change would force the structure to change - the only ones an architecture document owes an answer to.
Architecture Documentation	practice	Architecture Documentation	Writing down the decisions and their reasoning at an altitude that stays true long enough to be worth reading.
Architecture Fitness Function in CI Architecture Test, ArchUnit Test	practice	Fitness Functions	An executable check in the build that fails when an architectural constraint is violated, turning a design rule into a property the codebase cannot lose.
Architecture Principle	practice	Architecture Principles	A durable agreed rule that rules options out, stated with rationale and implications rather than as a slogan.
Architecture Principle	practice	Architecture Fundamentals	A durable, agreed rule that constrains design decisions in advance, stated with its rationale and its implications.
Architecture Style	concept	Architecture Styles	A system-level organising shape — layered, modular monolith, service-based, microservices, event-driven, space-based — chosen for the properties it makes cheap.
Architecture Style	concept	Architecture Fundamentals	A named, coarse-grained way of organising a whole system, as distinct from a pattern that solves one recurring problem inside it.
Architecture Viewpoint	concept	Architecture Documentation	A perspective on a system tailored to the concerns of a particular audience, recognising that no single diagram serves everyone.
Assumption Register	practice	Technical Constraints	The record of the numeric assumptions a design was sized against, monitored so the architecture announces when its own premises expire.
Automated Governance	practice	Fitness Functions	Encoding architectural rules as executable checks in the build pipeline, so conformance is verified continuously rather than reviewed periodically.
Big Ball of Mud	concept	Modularity	A system with no discernible structure, where every change requires understanding everything - usually the result of many locally rational decisions.
Boundary Traffic Cost Chattiness Tax, Decomposition Data Cost, Per-Hop Cost	concept	Coupling	The recurring cost of the data and coordination that cross a component boundary - paid on every request forever, and the number that decides whether a decomposition is affordable rather than merely tidy.
Capability Model	concept	Reference Models	A structured map of what a business does, independent of how it is organised or which systems support it, used to align technology investment with function.
Capacity Borrowing Capacity Reallocation, Priority Eviction, Shared Fleet Priority	practice	Architectural Drivers	Serving an unpredictable new load from an existing shared fleet by displacing lower-priority work, which requires that the displaceable work be identified and shaped to be interruptible before the demand arrives.
Change-Reason Cohesion Single Reason to Change, Axis of Change	practice	Cohesion	The working test for a module boundary - things belong together if they change for the same reason, at the same time, driven by the same stakeholder, and share invariants.
Cohesion	concept	Architecture Fundamentals	The degree to which everything inside one component belongs together and changes for the same reason.
Cohesion in Practice	concept	Cohesion	Whether the things inside a boundary belong together — measured by whether they change for the same reason and at the same time.
Common Coupling Shared Mutable State Coupling, Shared Database Coupling	concept	Coupling	Coupling through shared mutable state, where every participant constrains every other participant's ability to change - the one form of coupling with no natural upper bound.
Concern Restatement Tax Layer Tax, Shotgun Surgery	concept	Separation of Concerns	The fixed, permanent cost paid by every feature when architectural layers restate the same concern at several altitudes instead of separating different concerns.
Connascence Connascence of Meaning, Static Connascence	concept	Cohesion	A graded vocabulary for coupling that ranks each dependency by how hard it is to change and how far apart the parties are, so boundaries can be argued with a ranking instead of adjectives.
Constraint Discovery	practice	Requirements to Constraints	The systematic elicitation of the fixed conditions a solution must satisfy, distinguished from requirements because they are not negotiable and are rarely volunteered.
Constraint Expiry Dated Constraint, Constraint Provenance	practice	Requirements to Constraints	Recording every constraint with its source and its expiry date, so that temporary facts do not get permanently encoded into an architecture.
Conway's Law	concept	Architecture Fundamentals	Systems tend to mirror the communication structure of the organisation that builds them.
Coordination Cost Change Coupling Cost, Cross-Team Latency, Lockstep Tax	concept	Conway's Law	The delay and effort imposed on a change by the number of teams and services that must agree and release together - usually the dominant term in delivery lead time, and almost never instrumented.
Coordination Tax Cross-Team Feature Cost, Conway Misalignment Cost	concept	Conway's Law	The permanent, structural cost incurred when service boundaries are drawn on a different axis from the way work arrives - and the reason consolidating services is sometimes an architectural improvement.
Cost-Bearing Abstraction Budgeted Abstraction, Abstraction Over Finite Resources	concept	Abstraction & Encapsulation	The principle that any abstraction which lets a caller express arbitrary intent over a shared finite resource must also expose a budget - otherwise the feature is a denial-of-service surface.
Counterfactual Structure Test Driver Test, Would-The-Shape-Change Test	practice	Architectural Drivers	The one-question test that separates architectural drivers from important features - remove this requirement, and would the structure of the system change?
Coupling	concept	Architecture Fundamentals	The degree to which one component must know about, or change alongside, another.
Coupling in Practice	concept	Coupling	The kinds of coupling that actually hurt, ranked by how much they constrain independent change.
Cross-Cutting Concern	concept	Separation of Concerns	A responsibility that legitimately appears throughout a system rather than in one module, such as logging, authorisation, tracing or transaction management.
Cross-Functional Requirement	concept	Functional vs Non-Functional	A quality the system must exhibit across its features rather than a behaviour it must perform, so named because it cuts across all functionality.
Degradation Ladder	practice	Architecture Roles	A pre-agreed ordered list of capabilities the system sheds under load, with the ordering owned by the business and the mechanism owned by the architect.
Documentation Half-Life Doc Decay, Staleness Rate	concept	Architecture Documentation	The observation that architecture documentation decays in proportion to how much it restates current structure, and that the artefacts which survive are the ones that were always historical.
Encapsulation	concept	Architecture Fundamentals	Keeping a component's state private, so it can only be changed through operations that maintain its invariants.
Evolutionary Architecture	concept	Evolutionary Architecture	Designing for guided incremental change rather than for a correct end state, because the requirements that will matter most are not yet known.
Evolutionary Architecture	practice	Architecture Fundamentals	Designing for guided, incremental change rather than trying to get the structure right once, up front.
Fitness Function	practice	Architecture Fundamentals	An automated check that an architectural characteristic still holds, run continuously rather than reviewed occasionally.
Fitness Function Drift Vacuous Check, Silent Rule Decay	concept	Fitness Functions	The failure mode in which an architecture check keeps passing after it has stopped examining anything, so a green build certifies a rule that is no longer enforced.
Functional Cohesion	concept	Cohesion	The strongest form of cohesion, in which every element of a module contributes to a single well-defined task.
Functional vs Non-Functional Behaviour vs Quality of Behaviour	concept	Functional vs Non-Functional	Functional requirements say what the system does; non-functional requirements say how well, and only the second constrains structure.
Information Hiding	concept	Modularity	Designing module boundaries around the decisions most likely to change, so that a change is contained within one module.
Instagram's Early Scaling	case-study	Architecture Fundamentals	Instagram reached tens of millions of users on Django and PostgreSQL with a handful of engineers, by deliberately choosing boring technology and doing the simple thing first.
Inverse Conway Manoeuvre	practice	Conway's Law	Deliberately reorganising teams so that the architecture you want becomes the architecture the organisation naturally produces.
Last Responsible Moment	practice	Evolutionary Architecture	Defer an irreversible decision until the cost of deferring exceeds the cost of deciding - and define in advance the signal that says the moment has arrived.
Leaky Abstraction	concept	Abstraction & Encapsulation	An abstraction whose underlying implementation details become visible or consequential, requiring users to understand what it was meant to hide.
Modularity	concept	Architecture Fundamentals	The degree to which a system is composed of parts that can be understood, changed and replaced independently.
Modularity via the Modular Monolith Modulith	pattern	Modularity	A single deployable unit with strictly enforced internal module boundaries — the default most organisations should exhaust before distributing.
Non-Functional Budget Quality Attribute Budget, Latency Budget Allocation	practice	Functional vs Non-Functional	Splitting a system-level quality target into per-component allowances with named owners, so a change can be shown to have spent someone's allowance rather than merely argued about.
Non-Functional Requirement NFR, Quality Attribute	concept	Architecture Fundamentals	A requirement about how well the system must behave rather than what it must do — latency, availability, throughput, security, cost.
Principle Rationale	practice	Architecture Principles	The stated reasoning and implications attached to an architecture principle, without which the principle cannot be applied to a case its authors did not foresee.
Principle Statement Format Statement-Rationale-Implication, Testable Principle	practice	Architecture Principles	The four-part shape - statement, rationale, implications, exceptions - that turns an architecture principle from a preference into something that actually rules options out.