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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
One-Way Door Decision Type 1 Decision, Irreversible Decision concept Reversibility A decision that is very costly or impossible to reverse, warranting deliberation proportionate to that permanence.
Online Training Loop Continuous Training, Streaming Model Updates pattern Feature Freshness Training a model continuously on interaction events as they arrive rather than on a scheduled batch, trading the ability to gate a model artefact before serving for the ability to react to feedback within minutes.
Open Table Format Iceberg, Delta Lake, Hudi tool Open Table Formats A metadata layer over object storage files that provides atomic commits, schema evolution and time travel, turning a directory of files into a real table.
OpenAPI Swagger tool API & Integration A machine-readable specification format for HTTP APIs, from which documentation, clients, servers, mocks and validation can be generated.
OpenID Connect OIDC protocol Security Architecture An identity layer over OAuth 2.0 that adds a signed ID token asserting who the user is and how they authenticated.
OpenTelemetry OTel tool OpenTelemetry A vendor-neutral standard and toolset for generating, collecting and exporting traces, metrics and logs.
Operated Reliability Realised Availability concept Reliability vs Complexity The availability a system actually achieves in the hands of the team running it - as distinct from the availability its topology implies.
Operating Effectiveness concept Control Design vs Operation Whether a control actually ran, consistently, over a period — as distinct from whether it was well designed, and the harder of the two to demonstrate.
Operating Model concept Operating Models How an organisation arranges people, process, technology and governance to deliver its capabilities, which constrains architecture as strongly as any technical factor.
Operating Models concept Operating Models How an organisation arranges people, ownership and decision rights to deliver and run systems — which determines what architectures are viable.
Operational Burden Assessment practice Managed vs Self-Managed Quantifying the ongoing engineering effort a self-managed component requires, so it can be compared honestly with a managed service's price.
Operational Data Push pattern Reverse ETL Sending modelled analytical data back into operational tools, which turns a warehouse table into a production dependency with none of the guarantees.
Operational Readiness Go-Live Readiness, Launch Readiness practice Time to Market Defining go-live from the whole value stream rather than from the deployment, so the processes that receive a launch - returns, reconciliation, support, tax - are ready before customers arrive rather than week…
Operational Resilience Requirement concept Financial Services Regulation A supervisory expectation that a firm can continue delivering critical business services through disruption, expressed as an impact tolerance it must evidence.
Operational vs Analytical Store concept Polyglot Persistence The separation between the store serving the application's transactions and the one serving reporting and analysis, and the mechanism connecting them.
Operator Independence concept Digital Sovereignty The requirement that no foreign entity can be compelled to access or disclose data, which goes beyond where the bytes are stored to who controls the operator.
Optimistic Claim Conditional Assignment, Compare-and-Set Dispatch pattern Consistency Models Ranking candidates from deliberately stale data and resolving the race atomically at the moment of commitment, rather than locking during selection.
Optimistic Concurrency Control OCC, Compare-and-Set pattern Distributed Locking Allowing concurrent work without locks and detecting conflict at write time by checking that the underlying version has not changed.
Optimistic Update Reconciliation Optimistic UI Rollback, Client Reconciliation pattern Client State Architecture The policy deciding what happens when a change already shown to the user differs from what the server ultimately accepts - the part of optimistic UI where the real defects live.
Options-With-Consequences Never Present a Binary, Costed Alternatives practice Explaining Trade-offs Presenting a technical constraint as a set of costed options rather than as an objection, so the decision moves to the person accountable for the consequence with the information they need.
Organisational Constraints concept Organisational Constraints The structural, procedural and human limits that determine which designs can actually be built and operated here.
Organisational Readiness concept Organisational Constraints Whether an organisation has the skills, capacity, structure and appetite to operate a proposed architecture, independent of the design's technical merit.
Origin Isolation Sandbox Origin, User Content Origin practice Frontend Security Serving user-uploaded or untrusted content from a separate origin, so that content executing there has no access to the application's session, storage or DOM.
Origin Shield Shield Tier, Mid-Tier Cache, Request Collapsing Tier pattern Reverse Proxies An intermediate caching tier between edge caches and the origin that collapses many simultaneous misses into a single origin fetch - which is what makes multi-CDN and live streaming survivable for the origin.
Origin Shield Parent Cache, Mid-Tier Cache practice Content Delivery Networks An intermediate cache tier between edge locations and origin, so that hundreds of simultaneous edge misses become a handful of origin requests.
Orphaned Resource concept Waste Elimination Infrastructure that is billed but serves nothing, typically left behind when the thing it supported was deleted.
Outbound Dependency Census Egress-Derived Dependency Inventory, External Dependency Reconciliation practice Context Diagrams Deriving the list of systems a product depends on from four independent machine-readable registers instead of from memory, then deciding which of them belong on a diagram and which belong in a register.
Outbox Pattern Transactional Outbox pattern Sagas & Compensation Writing a message to a table in the same database transaction as the state change, then publishing it asynchronously, so the two cannot diverge.
Outbox Relay pattern Outbox The process that reads pending messages from an outbox table and publishes them to a broker, providing at-least-once delivery with no distributed transaction.
Outcome Certainty Taxonomy Retryability Classification, Four-State Error Model pattern API Error Handling Classifying every external response into definitely-failed-retryable, definitely-failed-terminal, definitely-succeeded, or unknown - and giving the fourth state a real resolution path rather than a guess.
Outcome Measurement practice Outcome Measurement Determining whether an architectural change achieved what it was meant to — the step most often skipped, which is why the same mistakes recur.
Outcome over Output concept Product Thinking Measuring and committing to changes in user or business behaviour rather than to the delivery of features.
Outlier Alerting Per-Tenant Alerting, Worst-Case Alerting practice Application Performance Monitoring Alerting on the worst-affected segment rather than on an aggregate, because in skewed populations the aggregate is dominated by the segment that is fine.
Output Validation Layer pattern Guardrails A deterministic check applied to model output before it is used, treating the model as an untrusted component.
Over-Classification Label Inflation, Maximum Propagation Collapse concept Sensitivity Labelling The state in which so much of an estate carries the highest sensitivity label that its controls become unworkable, and people route around them - producing less protection than a coarser scheme would.
Over-Engineering concept Pragmatism Building capability the requirements do not justify, paying its complexity cost continuously in exchange for flexibility that is rarely used.
Over-Fetching concept API Shapes for UI Transferring fields the interface will not display, which costs bandwidth and parse time on exactly the devices least able to afford them.
Over-the-Air Update OTA, Firmware Update practice OTA Updates Updating software on deployed physical devices remotely, where a failed update can require someone to physically visit the device.
Overload Recovery Time Overload Settling Time metric Stress Testing Wall-clock time from the moment load returns to normal until the system is fully healthy again, which is set by spare capacity rather than by service speed.
Overrule Threshold Review Intervention Test, Reversibility Test for Reviewers practice Mentoring The stated rule a reviewer uses to decide when to impose their own design over a workable one - reversal cost and blast radius, not personal preference - so that authorship stays with the engineer everywhere i…
OWASP Risks OWASP Top Ten concept OWASP Risks The recurring application vulnerability classes — and the architectural decisions that make each one structurally unlikely.
OWASP Top Ten practice Security Architecture A periodically updated consensus list of the most critical web application security risks, useful as a design-review checklist.
Ownership-First Decomposition Assign Owners Before Splitting, Logical Before Physical practice Database Migration Assigning each table a single owning team before splitting any code or data, because the ownership step costs nothing, removes the worst of the coupling immediately, and makes every subsequent step tractable.
Pace-Layered Application Strategy Pace Layering, PACE Layers practice Application Portfolio Management Sorting applications by how fast the business needs them to change - records slowly, differentiators quarterly, innovations weekly - and giving each layer its own governance funding and integration rules inste…
PACELC concept CAP & PACELC An extension of CAP stating that during a partition you trade availability against consistency, and else — in normal operation — you trade latency against consistency.
Page and Ticket Routing practice Alerting Deciding for each monitored condition whether it warrants immediate human interruption or asynchronous handling, and enforcing the distinction.
Page Budget Pages Per Shift, Alert Budget metric On-Call An explicit ceiling on how many pages a shift may generate, treated as a limit the team manages against rather than as an outcome it observes.
Pager Boundary Platform On-Call Boundary, Injected Component Ownership Line practice Platform Engineering The written line in a platform contract that says which symptoms page the platform team and which page the consuming team, and how a single signal tells the two apart during an incident.
Pagination Design Cursor Pagination, Keyset Pagination practice Pagination & Filtering Returning large result sets in pages, where offset-based paging is both slow at depth and incorrect under concurrent writes.
Parallel Run practice Parallel Run Operating the old and new systems simultaneously on the same inputs and comparing outputs, to build evidence that the replacement is correct before relying on it.
Parallelism and Concurrency concept Concurrency The distinction between structuring work so it can make progress independently and actually executing work simultaneously on multiple cores.
Partial Deployment Verification Artefact Completeness Check, Fleet Convergence Verification practice Segregation of Duties Machine confirmation that every target in a fleet is running the intended artefact, independently checked, so that an incomplete rollout cannot present itself as a finished one.
Partial Hydration Islands Architecture, Selective Hydration pattern Hydration Cost Attaching client-side interactivity only to the components that need it, rather than reconstructing the whole page's component tree in the browser.
Partial Index Filtered Index concept Indexing An index built over only the rows matching a predicate, so it is far smaller and cheaper to maintain than a full index.
Partition Assignment concept Competing Consumers The mapping of partitions to consumer instances that determines parallelism, ordering guarantees and what happens when the consumer set changes.
Partition Count Immutability Fixed Partition Count, Key-to-Partition Remap Hazard concept Partition Keys & Ordering The partition count of a keyed log is effectively permanent, because raising it changes which partition a key hashes to and therefore breaks per-key ordering and every table rebuilt by replaying that log.
Partition Key Skew Hot Partition, Key Skew concept Partition Keys & Ordering One partition receiving disproportionate traffic because a small number of key values dominate, capping throughput at what a single consumer can handle.
Partition Pruning concept Storage Layout & Partitioning The query engine skipping entire partitions whose values cannot match the filter, which is where most large-table query performance comes from.
Partition Tolerance concept CAP & PACELC The ability to keep operating when the network drops or delays messages between nodes — not a choice, but a property of any system spanning more than one machine.
Partitioning and Sharding concept Partitioning & Sharding Splitting data by a key — within one database for manageability, or across databases for capacity and isolation.