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Terminology

2205 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 areas2205 Architecture Fundamentals77 Distributed Systems107 Data Architecture110 Cloud Architecture94 Networking88 API & Integration Architecture82 Reliability & Resilience75 Observability70 Performance & Capacity Engineering72 Security Architecture86 Cost Architecture & FinOps71 Business Architecture67 Architecture Communication67 Enterprise Architecture66 Legacy Modernization71 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 concept794 practice734 pattern368 metric125 case-study77 tool62 protocol45

2205 terms shown.

Term Kind Topic What it is
Error Budget metric Reliability & Resilience The amount of unreliability an SLO permits, treated as a resource that feature velocity spends.
Error Budget Policy practice Error Budgets The pre-agreed consequences of exhausting an error budget, which is what turns an SLO from a metric into a decision-making mechanism.
Error Fingerprinting Issue Grouping, Event Deduplication pattern Observability Deriving a stable identifier from an error's invariant attributes so that many occurrences collapse into one actionable issue - and the two directions in which the heuristic fails damagingly.
Escalation Threshold practice Human in the Loop The rule determining when a model's output is acted on automatically and when it is routed to a person.
Escape Hatch Drop to Primitives, Graduated Abstraction, Opt-Out Path concept Abstraction Level Choice A supported way for a team to bypass part of a platform abstraction and work with the underlying primitives - which is what makes an abstraction safe to adopt and what supplies the platform's most valuable roa…
Escape Hatch Progressive Disclosure, Drop-Down Path practice Abstraction Level Choice A supported route from a platform's simple default down to the underlying primitives - so a team with an unusual need adapts within the platform rather than leaving it.
Estimate Range With Narrowing Cost Three-Part Estimate, Buy Certainty practice Estimation Answering an estimation question with a range, the drivers of its width, and what it would cost to narrow it - which turns an estimation problem into a decision the asker can make.
Estimation Range practice Estimation Expressing an estimate as an interval with a stated confidence rather than as a single number, because a point estimate misrepresents what is known.
Ethical Impact Assessment practice Ethics in Architecture Deliberately examining who could be harmed by a system and how, at the point in design where the answer can still change the outcome.
Ethics in Architecture concept Ethics in Architecture The consequences of architectural decisions for people who did not choose them — and the architect's responsibility for the ones that are foreseeable.
ETL and ELT practice ETL & ELT Whether to transform before loading or after — a choice that follows from where compute is cheap and who owns the transformation.
ETL vs ELT concept Data Architecture Whether data is transformed before loading into the target or after it, which decides where the compute happens and how much raw history you keep.
Etsy's Continuous Deployment case-study Software Architecture Etsy moved from infrequent, risky releases to dozens of deploys a day, demonstrating that deployment frequency and stability improve together rather than trading off.
Etsy: Deploying Fifty Times a Day Code as Craft case-study Continuous Integration Discipline Etsy demonstrated that very frequent small deployments reduce risk rather than increasing it, and paired it with blameless postmortems.
Evaluation Gate Coverage Gate Scope Ratio, Release Evaluation Coverage metric Model Evaluation & Red-Teaming The share of a feature's real failure surface that its release evaluation actually exercises, which determines whether a passed gate is evidence of safety or evidence that the suite is stale.
Event Notification vs Event-Carried State concept Event-Driven Integration Whether an event carries only the fact that something happened, or also the data a consumer needs to act on it.
Event Sourcing pattern Data Architecture Storing the full sequence of state-changing events as the system of record, and deriving current state by replaying them.
Event Sourcing in Practice pattern Event Sourcing Storing state as an immutable sequence of events and deriving current state by replay — powerful where history is the domain, expensive everywhere else.
Event Sourcing in Practice Event Store, Append-Only State pattern Event Sourcing Storing the sequence of changes rather than current state, the capabilities that follow, and the erasure problem that must be designed for on day one.
Event Store tool Event Sourcing An append-only store of domain events organised into per-entity streams, serving as the system of record rather than as a log beside it.
Event Stream tool Distributed Systems An append-only, retained log of events that many independent consumers read at their own position, and can re-read.
Event Stream Versioning pattern Event Sourcing Transforming an old event version into the current shape when it is read, allowing a stored event history to be interpreted by evolved code.
Event Streaming Distributed Log, Commit Log pattern Event Streaming A durable ordered log of facts that many independent consumers read at their own pace, retaining events after consumption rather than deleting them.
Event Time Versus Processing Time concept Windowing The distinction between when something happened and when the system saw it, which determines whether results are reproducible.
Event Time vs Processing Time concept Windowing The distinction between when something happened in the world and when the system got round to handling it.
Event Upcasting pattern Event Sourcing Transforming an old event's stored form into the current shape as it is read, so historical events remain replayable after the schema changes.
Event Versioning practice Event-Driven Integration Evolving event schemas without breaking consumers that may read messages written months earlier.
Event-Driven Architecture EDA pattern Event-Driven Architecture A style in which components communicate by publishing and reacting to facts, rather than by calling each other and waiting.
Event-Driven Architecture EDA pattern Architecture Patterns A style in which components communicate by emitting and reacting to facts about what happened, rather than by calling each other.
Event-Driven Integration pattern Event-Driven Integration Integrating systems by delivering events rather than by polling or synchronous calls — including the delivery guarantees the receiver must be told about.
Eventual Consistency concept Distributed Systems A guarantee that replicas will converge to the same value if updates stop, with no bound on how long reads may be stale.
Evidence Based Approval practice Change Advisory vs Automated Gates Replacing a human judgement about whether a change is safe with a machine-produced record of the checks it passed, assessed once for the class rather than per instance.
Evidence by Construction practice Audit Evidence Designing systems so that operating them produces the audit evidence automatically, rather than reconstructing it from screenshots when an assessment arrives.
Evidence By-Product Evidence Automation, Continuous Evidence practice Audit Evidence Audit evidence produced automatically by the control operating, rather than assembled by engineers before each audit.
Evidence Transferability Context Matching, Scale Applicability, Case Study Fit concept Explaining Trade-offs The degree to which a finding from another organisation's system applies to yours, determined by similarity of workload shape, scale and constraints - and the discipline of extracting the question rather than …
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.
Exactly-Once Semantics EOS, Effectively-Once concept Exactly-Once Semantics The guarantee that each input record affects the output state precisely once, achieved through atomic state-and-offset commits rather than through delivering messages once.
Exception and Waiver Management practice Exception & Waiver Management The formal process for permitting a deviation from a standard, with a named risk owner, a stated expiry and a remediation plan.
Exception Path Frequency Normal Exceptions, Physical Divergence Rate metric Physical-World Failure Modes The rate at which physical operations diverge from the system's model - a business metric to be managed rather than a defect rate to be eliminated, and the input to how the exception path should be resourced.
Exception Register Waiver Management, Control Deviation Record, Risk Acceptance Log practice Exception & Waiver Management A recorded, owned, time-bounded set of approved deviations from a control - which is what makes a control survivable, and whose aggregate is the best available evidence about whether the control fits reality.
Exception Register Waiver Log, Standard Deviation Record practice Technology Standards A record of every deviation from a standard, with approver, rationale and review date - which makes violations deliberate rather than silent and tells you whether the standard describes the right rule.
Exception Tail Long Tail of Cases, Manual Remainder concept Business Processes The minority of cases an automated process cannot handle, whose automation cost per case rises steeply, so the economically correct end state is usually a smaller manual path rather than none.
Exception Union Requirements Union, Consolidation Scope Creep concept Application Rationalisation The failure mode of consolidation programmes in which the replacement system inherits the union of every source system's local exceptions, making it more complex than any system it replaces.
Executable Reference Architecture Service Template, Golden Path Template pattern Reference Architectures A template that generates a working, compliant, observable, deployable service - replacing a reference document with something teams adopt because it is the fastest way to start.
Execution Model Fit concept Serverless vs Containers Matching a workload's traffic shape, duration and state requirements to the execution model that suits it, rather than choosing one model for everything.
Executive Communication practice Presenting to Executives Presenting technical matters to an audience that owns outcomes and money, in a form that supports a decision within their attention span.
Executive Summary Discipline practice Presenting to Executives Leading with the recommendation and its business consequence, compressed to what an executive audience can act on in a few minutes.
Exemplar concept OpenTelemetry A trace identifier attached to a metric data point, linking an aggregate measurement directly to a concrete request that produced it.
Exit and Concentration Risk concept Exit & Concentration Risk The regulatory concern that an institution cannot leave a critical provider, and that too much of the sector depends on the same few providers.
Exit Cost Switching Cost, Cost of Exit metric Build vs Buy The engineering effort and elapsed time required to move off a vendor, which sets both the real price of lock-in and the team's negotiating position at renewal.
Expand and Contract Parallel Change, Expand-Migrate-Contract pattern Database Migration Under CD Changing a schema or contract in three deployable steps so old and new code are correct at every moment.
Expand and Contract Migration Parallel Change, Expand-Migrate-Contract practice Data Governance Changing a schema through a sequence of individually backward-compatible steps, so old and new application versions can run simultaneously.
Expand-Contract Migration Parallel Change, Add-Migrate-Remove, N-1 Compatibility pattern Zero-Downtime Migration Making a breaking change as a sequence of individually reversible steps - add the new alongside the old, migrate readers and writers across, then remove the old - so that at no point is a rollback destructive.
Expensive-to-Change Core concept Delivery vs Maintainability The small part of a system whose shape is copied into stored data and into other people's code, where a shortcut cannot be repaid locally - so deliberate debt belongs everywhere else.
Explained-Difference Criterion Shadow Exit Criterion, Zero Unexplained Differences practice Parallel Run Ending a shadow or parallel run when every observed difference has been explained, rather than when differences reach zero - because zero is unachievable and unexplained differences are by definition the dange…
Explaining Trade-offs practice Explaining Trade-offs Presenting a choice so that the audience can exercise the judgement that is genuinely theirs, in the terms they actually think in.
Explicit Staleness As-Of Semantics, Freshness Disclosure practice Digital Twin Publishing how old a modelled or cached value is alongside the value itself, so consumers can judge whether it is usable rather than assuming it is current.
Exponential Backoff pattern Distributed Systems Increasing the wait between retries geometrically, with random jitter, so that failures do not synchronise into a stampede.
External Key Store Hold Your Own Key, External Key Manager, HYOK pattern Digital Sovereignty Holding the key-unwrapping function in a system the cloud provider does not operate so that a decrypt requires a call outward, converting a contractual promise about foreign access into a technical dependency.