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

794 terms shown.

Term	Kind	Topic	What it is
Resource Requests and Limits	concept	Kubernetes	The declared minimum a container is guaranteed (request) and the maximum it may consume (limit) — the two numbers that determine scheduling, packing and throttling.
Restore Granularity Recovery Unit, Restore Scope	concept	RTO & RPO	The smallest unit a recovery procedure can return without disturbing everything stored alongside it, which sets the real recovery time for any incident that affects a subset of the data.
Restore-Only Rollback No-Downgrade Path, Backup-Dependent Reversal	concept	Rollback & Forward Fix	The state of a system that cannot be returned to its previous version by deploying it, so the only reversal available is restoring from backup - which converts a minutes-long rollback into a recovery operation…
Resync Horizon Tombstone Retention Window, Full Resync Threshold	concept	Sync & Conflict Resolution	The age of the oldest change a server can still describe as a delta - beyond which a returning client must take a full snapshot or it will silently keep records that were deleted.
Retention Clock Retention Trigger Event, Governing Event	concept	Records Retention & Legal Hold	The business event from which a retention period is measured - not the row's creation - which must be recomputed rather than stored because late events move it.
Retrieval Grounding Grounded Generation	concept	RAG Architecture	Constraining a model's answer to content retrieved from an authoritative corpus, with citations and an abstention path - so that output quality becomes a retrieval problem rather than a model problem.
Retrieval-Cost Trap Archival Access Cost, Cold Tier Scan Penalty	concept	Storage Costs	The failure where moving data to an archival tier saves storage cost and a scanning access pattern then spends more on retrieval than the tiering saved.
Retryable Error	concept	API Error Handling	An error whose cause may resolve on its own, which a client may safely attempt again — as distinct from one that will fail identically.
Reverse Compatibility Window Revert Window, Rollback Precondition	concept	Rollback & Forward Fix	The period during which every live consumer must still accept the previous version's output, because a rollback of one component is a forward-incompatible change for everything downstream of it.
Reversibility	concept	Trade-off Fundamentals	The property of a decision that determines how much analysis it deserves, since a cheaply reversible choice can be tested rather than debated.
Reversible Decision Two-Way Door	concept	Architecture Decision-Making	A choice that can be undone cheaply, and which therefore deserves far less deliberation than an irreversible one.
Review Scope Mismatch Blast-Radius Blindness in Review, Scope-Blind Approval	concept	Systems Thinking	A control that inspects the mechanics of a change while the risk lives in its reach - so the review passes honestly and the change still destroys something.
Revocation Window Token Lifetime as SLA, Local Validation Trade	concept	Tokens & JWTs	The period during which a revoked credential remains accepted, which for locally-validated tokens is exactly the token lifetime - the unavoidable price of removing the identity provider from the request path.
Right to Erasure Right to be Forgotten	concept	Erasure vs Immutability	An individual's right to have their personal data deleted, which collides directly with append-only and immutable architectures.
Risk Appetite	concept	Risk Appetite	The amount and type of risk an organisation is willing to accept in pursuit of its objectives, stated explicitly enough to guide a design decision.
Risk Tolerance Statement	concept	Risk Appetite	The board-level declaration of how much of each risk type the organisation will accept, which is what tells an architect which risks may be accepted without escalation.
Role Explosion	concept	Authorization	The proliferation of narrowly-scoped roles that occurs when RBAC is used to express rules that actually depend on context.
Rolling Update Surge	concept	Deployment Strategies	The extra capacity a rolling deployment temporarily adds, and the unavailability it is permitted, which together decide whether the rollout is safe under load.
Route Propagation	concept	Routing & BGP	Automatically inserting routes learned from a VPN or dedicated connection into a route table, rather than maintaining them by hand.
Route Table	concept	Subnetting	The set of rules deciding where traffic leaving a subnet is sent, and the thing that actually makes a subnet public or private.
Runtime Compliance Drift Plan-Time Blind Spot, Post-Apply Divergence	concept	Architecture Compliance Checks	The growing gap between what infrastructure code declares and what the running estate actually looks like, which a pipeline-based policy check cannot see and therefore reports as compliant.
Runtime Composition Risk Remote Module Risk, Deferred Integration Failure	concept	Module Federation	The class of failures created by resolving module existence, export shape and shared-dependency versions in the user's browser instead of at build time - including the inability to roll back a remote you do not own.
Saga Isolation Anomaly	concept	Saga	The intermediate states visible to other transactions during a saga, because a saga provides atomicity and durability but not isolation.
Saturation Point	concept	Throughput	The load level beyond which additional demand produces queueing and latency growth rather than additional completed work.
Scalability	concept	Distributed Systems	The ability to handle growing load by adding resources, ideally with cost rising no faster than the load.
Scale Cube	concept	Horizontal vs Vertical Scaling	A model describing three independent axes of scaling — cloning, functional decomposition, and data partitioning — each addressing a different limit.
Scheduler Control Plane	concept	Workflow Schedulers	The orchestrator's own state and availability, which becomes a critical dependency for every pipeline it runs.
Schema Compatibility Mode	concept	Streaming Schema Evolution	The rule stating which schema changes a registry will accept, which encodes whether producers or consumers are expected to upgrade first.
Schema Evolution	concept	Data Lakes & Lakehouses	Changing a table's structure over time while keeping existing data readable and existing consumers working.
Second-System Effect	concept	Trade-off Fundamentals	The tendency for a replacement system to accumulate every capability the first one lacked, producing something more complex than either the old system or the problem requires.
Secret Zero Bootstrapping Problem	concept	Secrets Management	The credential a workload needs in order to authenticate to the secret manager — the one secret that cannot itself be stored in the secret manager.
Secret Zero Problem	concept	Secrets Management	The credential a workload needs in order to authenticate to the secret manager, which cannot itself be stored in the secret manager.
Sector Cloud Rules	concept	Sector Cloud Rules	Sector-specific rules governing cloud use — outsourcing notification, audit rights, concentration risk and exit — which shape provider and service choices.
Security Group Sprawl	concept	Network Security	The accumulation of firewall and security group rules that nobody can safely remove, producing a permissive posture nobody chose.
Security versus Usability	concept	Security vs Usability	Controls that impose too much friction get circumvented — so the usable control is frequently the more secure one.
Segregation of Duties SoD, Separation of Duties	concept	Segregation of Duties	Ensuring no single individual can both initiate and approve a sensitive action, so that fraud or error requires collusion.
Selective Reliability Partial Reliability, Deadline-Aware Delivery	concept	Pipes and Filters	Retransmitting only what is still useful and discarding what has expired - because for time-sensitive data, late delivery consumes capacity without providing value.
Selector Dependency Label Contract, Implicit Platform Dependency	concept	Cluster Architecture	A production dependency that exists only as a string matching a label or annotation, so it is invisible to code search and to release notes, and a platform upgrade that renames the label silently removes it.
Self-Service versus Governed	concept	Self-Service vs Governed	Balancing analyst autonomy against consistency — resolved by tiers and enforced definitions rather than by restricting access.
Semantic Coupling Meaning Drift, Invisible Event Coupling	concept	Publish/Subscribe	Dependence on what an event or field means rather than on its shape - the coupling that survives every schema check, breaks nothing when violated, and is the hardest failure to detect in an event-driven system.
Semantic Schema Break Wire-Compatible Meaning Change	concept	Streaming Schema Evolution	A change that keeps a field's wire format valid while changing what its values mean, so every compatibility check passes and every consumer computes a wrong answer without raising an error.
Sensitivity Propagation	concept	Sensitivity Labelling	The rule that a derived dataset inherits the highest sensitivity of its inputs unless a named transformation demonstrably lowers it.
Separation of Concerns	concept	Separation of Concerns	Organising a system so that one kind of change touches one place, and so that different concerns can fail and scale independently.
Separation of Concerns	concept	Architecture Fundamentals	Organising a system so each part addresses one concern, and a change to that concern touches one part.
Server State Versus UI State	concept	Client State Architecture	The distinction between data owned elsewhere and cached locally, and state that exists only in this session — conflating them causes most client state bugs.
Server-Side Request Forgery SSRF	concept	OWASP Risks	Inducing a server to make an HTTP request to an attacker-chosen destination, turning it into a proxy into networks and services the attacker cannot reach directly.
Serverless	concept	Cloud Architecture	A model where the provider allocates and scales compute per request, and you are billed for execution rather than for provisioned capacity.
Serverless Cold Start	concept	Serverless	The additional latency when a function invocation must allocate and initialise a new execution environment rather than reusing a warm one.
Serverless Compute in Practice Functions as a Service, FaaS	concept	Serverless	Compute billed per invocation with no capacity to manage — excellent for bursty low-duty-cycle work, expensive and constrained for sustained load.
Service Boundary	concept	Software Architecture	The line separating what one service owns and is accountable for from what it must ask another service about.
Service Catalogue Entry	concept	Internal Developer Platform	The record that makes a service a first-class object in the platform — owner, dependencies, docs, runbooks and health in one place with a single identity.
Service Discovery	concept	Distributed Systems	The mechanism by which a caller finds a currently healthy network address for a service whose instances are ephemeral.
Service Level Agreement SLA	concept	Reliability & Resilience	A contractual commitment about service level, with a defined remedy — usually a service credit — when it is missed.
Service Mesh Networking	concept	Service Mesh Networking	What a mesh actually does at the network level, the cost per hop, and the shift from sidecar to shared-proxy models.
Service Mesh Operational Cost	concept	Service Mesh Operations	The ongoing engineering burden a mesh imposes — upgrades, proxy debugging, latency overhead and control-plane availability — weighed against the capabilities it provides.
Service Quota Service Limit	concept	Cloud Governance	A per-account, per-region cap on how much of a resource may be used — a common and easily-avoided cause of scaling failures and DR failures.
Service Stub Fidelity	concept	Service Virtualisation	How faithfully a stand-in dependency reproduces the real one's behaviour — including its errors, latency and limits — which bounds what testing against it proves.
Serving Latency Budget	concept	Real-Time Serving Layer	The end-to-end time from an event occurring to its effect being queryable, allocated across ingest, processing and serving.
Serving Path Divergence Per-Pool Quality Drift, Heterogeneous Fleet Skew	concept	AI Observability	One configuration in a fleet of otherwise identical inference paths behaving differently from its peers - detectable by comparing paths against each other, and invisible to any metric averaged across them.
Shared Database Integration Integration Database	concept	Legacy Integration	Two or more applications reading and writing the same database directly — the most damaging integration pattern and the hardest to unwind.