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
Rightsizing	practice	Cost & FinOps	Matching provisioned resources to observed demand, rather than to the guess made when they were created.
Role Explosion	concept	Authorization	The proliferation of narrowly-scoped roles that occurs when RBAC is used to express rules that actually depend on context.
Round-Trip Time RTT, Latency Floor	metric	Network Performance	The time for a packet to travel to a destination and back — a physical floor that no application optimisation can reduce.
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.
RTO and RPO Recovery Time Objective, Recovery Point Objective	metric	Reliability & Resilience	How long recovery may take (RTO) and how much data may be lost (RPO), the two numbers that determine the cost of a resilience design.
Runbook Playbook	practice	Observability	A short, actionable document telling an on-call engineer what an alert means, what to check, and what the safe mitigations are.
Runbook Quality	practice	Incident Management	The properties that make an operational procedure usable by a tired responder under pressure, as opposed to a document that merely exists.
Saga	pattern	Distributed Systems	A sequence of local transactions across services where each step has a compensating action that semantically undoes it if a later step fails.
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.
Saga Orchestrator	pattern	Sagas & Compensation	A component that explicitly drives a saga's steps and compensations, holding the flow in one place rather than distributing it across event subscriptions.
Salesforce's Metadata-Driven Multi-Tenancy	case-study	Data Architecture	Salesforce serves every customer from shared infrastructure with a single physical schema, storing customer-specific data structures as metadata rather than as separate tables.
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.
Schema Evolution	concept	Data Lakes & Lakehouses	Changing a table's structure over time while keeping existing data readable and existing consumers working.
Seam Identification	practice	Strangler Fig	Locating the places in a legacy system where behaviour can be intercepted and redirected, which determines whether an incremental migration is feasible at all.
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.
Secrets Management	practice	Security Architecture	Storing, distributing, rotating and auditing credentials so that they never live in code, images or configuration files.
Security Group Firewall Rules, NSG	tool	Networking	A stateful, instance-level firewall that allows specified traffic and denies everything else by default.
Security vs Usability	concept	Architecture Decision-Making	A trade-off that is usually resolved by varying the control with the value of the action, rather than by choosing a uniform level of friction.
Semantic Cache	pattern	AI-Era Architecture	Caching model responses keyed by the meaning of the request rather than by its exact text, so near-duplicate questions are served without a model call.
Semantic Diffing of API Schemas	practice	Backward Compatibility	Comparing the published contract between builds and failing the build on a breaking change, so compatibility is mechanical rather than remembered.
Semantic Versioning SemVer	practice	API Versioning	A version scheme where the number itself states the compatibility promise — major for breaking, minor for additive, patch for fixes.
Separation of Concerns	concept	Architecture Fundamentals	Organising a system so each part addresses one concern, and a change to that concern touches one part.
Sequence Diagram	practice	Architecture Communication	A diagram showing the ordered exchange of messages between participants over time, used to make an interaction's control flow and failure points explicit.
Server-Sent Events SSE, EventSource	protocol	WebSockets & Realtime	A one-way streaming protocol over plain HTTP in which the server pushes text events to the client on a long-lived response.
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.
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 Control Policy SCP, Azure Policy, Organization Policy	tool	Landing Zones	An organisation-level guardrail that limits what any identity in an account may do, regardless of the permissions granted within that account.
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 Level Indicator SLI	metric	Reliability & Resilience	The actual measurement of a service's behaviour that an objective is set against — a ratio of good events to valid events.
Service Level Objective SLO	metric	Reliability & Resilience	An internal target for a service level indicator, set below the level at which users notice, and used to decide whether to ship or to stabilise.
Service Mesh	tool	Architecture Patterns	An infrastructure layer of sidecar proxies that handles service-to-service networking — mTLS, retries, timeouts, routing, telemetry — outside the application.
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 Registry	tool	Service Discovery	The database of currently available service instances and their addresses, maintained by registration and pruned by health checking.
Severity Levels SEV Levels	practice	Reliability & Resilience	A predefined scale of incident impact that determines who is woken, how fast, and what process applies.
Shadow Comparison	pattern	Parallel Run	Running a new implementation alongside the old on real traffic, comparing outputs without the new system affecting users.
Shard Key Selection	practice	Sharding Patterns	Choosing the attribute that determines a record's partition, which fixes the system's distribution, query patterns and future flexibility.
Sharding Horizontal Partitioning	pattern	Data Architecture	Splitting one dataset across multiple independent databases by a partition key, so that each holds a disjoint subset.
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.
Shared Responsibility Model	concept	Managed Services	The division of duties between provider and customer, which shifts with the service model and is routinely misunderstood in the customer's disfavour.
Shopify's Pods and Modular Monolith	case-study	Architecture Patterns	Shopify handles Black Friday scale with isolated pods — complete stacks each serving a subset of merchants — while keeping the application itself a deliberately modular monolith.
Shuffle Sharding	pattern	Distributed Systems	Assigning each customer a random combination of workers rather than a fixed shard, so that any two customers rarely share their whole set.
Sidecar	pattern	Architecture Patterns	Deploying a helper process alongside the main application in the same unit, to supply cross-cutting behaviour without changing the application.
Six Rs of Migration 6 Rs, Migration Strategies	concept	Legacy Modernization	The standard menu of options for each application in a migration — rehost, replatform, refactor, repurchase, retire, retain.
Slack's Cellular Migration	case-study	Cloud Architecture	After repeated availability-zone-level incidents, Slack rebuilt its infrastructure into per-zone cells with the ability to drain traffic away from a failing zone in minutes.
Slowly Changing Dimension SCD	pattern	Data Warehousing	A strategy for handling attributes that change over time, deciding whether history is preserved and how facts attach to the correct version.
Snapshotting	pattern	Event Sourcing	Periodically storing an aggregate's computed state so it can be loaded without replaying its entire event history.
Soak Test	practice	Soak Testing	Running sustained realistic load for hours or days to expose defects that accumulate over time rather than appearing under peak load.
Software Bill of Materials SBOM	tool	Supply Chain Security	A machine-readable inventory of every component and dependency in a piece of software, including transitive ones, used to answer exposure questions quickly.
SOLID	practice	Software Architecture	Five object-oriented design principles — single responsibility, open/closed, Liskov substitution, interface segregation, dependency inversion.
Solution Architecture	concept	Architecture Fundamentals	The design of a specific system that satisfies a specific business problem under a specific set of constraints.
Source NAT SNAT, Masquerading	concept	NAT & Egress	Rewriting the source address of outbound packets so that many private addresses share one public address, with a translation table mapping replies back.
Source Triangulation	practice	Research & Evaluation	Confirming a technical claim from several independent sources of differing type, because most available material is marketing or an unrepresentative anecdote.
Spec-First Development Design-First	practice	API Documentation	Writing and reviewing the API specification before implementing, so the contract is designed deliberately rather than emerging from code.
Spike and Prototype	practice	Deciding Under Uncertainty	A time-boxed experiment run to reduce uncertainty about a specific question, producing evidence rather than a component.