Terminology

681 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 areas681 Architecture Fundamentals38 Distributed Systems73 Data Architecture71 Cloud Architecture55 Networking51 API & Integration Architecture45 Reliability & Resilience40 Observability33 Performance & Capacity Engineering34 Security Architecture50 Cost Architecture & FinOps12 Business Architecture9 Architecture Communication8 Enterprise Architecture8 Legacy Modernization11 AI-Era Architecture34 Software Architecture & Engineering37 Architecture Patterns34 Architecture Decision-Making30 The Architect's Meta-Skills8

Kind Any concept258 practice180 pattern127 protocol32 tool32 case-study26 metric26

258 terms shown.

Term	Kind	Topic	What it is
Query Plan Regression	concept	Database Performance	A sudden latency increase caused by the database optimiser choosing a different execution plan for an unchanged query, typically after statistics or data volume change.
Quorum	concept	Distributed Systems	A minimum number of nodes that must acknowledge an operation for it to count, chosen so that read and write sets are guaranteed to overlap.
Re-architect vs Rebuild	concept	Legacy Modernization	Restructuring an existing system incrementally versus writing a replacement from scratch — and the strong evidence that incremental wins.
Read Timeout Socket Timeout	concept	Timeouts & Deadlines	The bound on how long a client waits for response data after a connection is established — distinct from the connect timeout, and the one that usually matters.
Read-Your-Writes Consistency Read-After-Write	concept	Consistency Models	A session guarantee that a client always sees its own updates, even when reads are served from replicas that may lag.
Redundancy	concept	Reliability & Resilience	Having more instances of a component than the load requires, so that failures can be absorbed without loss of service.
Refresh Token	concept	Tokens & JWTs	A long-lived credential used solely to obtain new short-lived access tokens, so sessions can persist without long-lived access tokens circulating.
Regulatory Constraint	concept	Business Architecture	A legal requirement that removes design options — and one that must be established early, because it is not negotiable and is expensive to retrofit.
Request-Reply and Fire-and-Forget	concept	Sync vs Async	The two interaction shapes available between components, differing in whether the caller waits for a result and therefore in whether availability compounds.
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.
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.
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.
Right to Erasure Right to be Forgotten	concept	Data Lifecycle & Retention	A data subject's right to have their personal data deleted, and an obligation that reaches every copy an architecture has 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.
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.
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.
Schema Evolution	concept	Data Lakes & Lakehouses	Changing a table's structure over time while keeping existing data readable and existing consumers working.
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.
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.
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-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 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 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.
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.
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.
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.
Split Brain	concept	Distributed Systems	A partition in which two halves of a cluster each believe they are authoritative, and both accept writes.
Split Vote	concept	Leader Election	An election in which no candidate obtains a majority, so the term ends with no leader and the process must repeat.
SQL vs NoSQL	concept	Architecture Decision-Making	A choice driven by access patterns, consistency requirements and query flexibility — not by data volume, which is the reason usually given.
Stateful Packet Filtering	concept	Firewalls & Security Groups	Filtering that tracks connection state, so return traffic for an allowed outbound connection is permitted automatically.
Static Stability	concept	Reliability & Resilience	The property that a system keeps working on its existing state when its control plane or dependencies are unavailable, rather than needing them to keep running.
Stream-Table Duality	concept	Streaming Data	The equivalence between a stream of changes and a table of current state — each can be derived from the other.
Strong vs Eventual Consistency	concept	Architecture Decision-Making	A per-operation decision, not a per-system one: whether this specific read must reflect every completed write.
Style versus Pattern	concept	Architecture Styles	The distinction between a system-wide organising structure and a reusable solution to a recurring problem within it.
Subject Naming Strategy	concept	Schema Registry	How schemas are keyed in a registry — per topic, per record type, or both — which determines whether one topic may carry several event types.
Subnet	concept	Networking	A subdivision of a network's address range, used as the unit of routing and, in cloud, of availability-zone placement.
Surrogate Key Synthetic Key	concept	Relational Modelling	A system-generated identifier with no business meaning, used as the primary key instead of a naturally occurring business value.
Symptom-Based Alerting	concept	Alerting	Alerting on degradation the user experiences rather than on the internal conditions that might cause it.
Synchronous vs Asynchronous Communication	concept	Architecture Decision-Making	Whether the caller waits for the callee's answer — decided by whether the caller's outcome depends on it, not by latency or taste.
Synchronous vs Asynchronous Replication	concept	Replication	Whether a write is acknowledged only after a replica has it, trading write latency against the amount of data a failure can lose.
Team Topologies	concept	Conway's Law	A model of four team types and three interaction modes used to design an organisation deliberately for a target architecture and flow of change.
Technical Debt	concept	Software Architecture	The future cost incurred by choosing an expedient implementation now instead of the better one.
Temporal Coupling	concept	Coupling	A dependency in which one component requires another to be available at the same moment, so the availability of both is required for either to work.
Terraform State IaC State File	concept	Infrastructure as Code	The file mapping declared resources to real infrastructure, without which the tool cannot tell what it already created — and which becomes critical infrastructure in its own right.
Testing Strategy Shape	concept	Testing Strategies	The distribution of tests across levels, chosen so that feedback is fast where it can be and confidence is real where it must be.
Thundering Herd	concept	Distributed Systems	A large number of clients acting simultaneously because they were synchronised by a shared event, producing a spike that the steady-state design never sized for.
Time Travel Data Versioning, Snapshot Query	concept	Data Lakes & Lakehouses	Querying a table as it existed at a previous version or timestamp, made possible by keeping the metadata and files of prior commits.
Toil	concept	Reliability Culture	Manual, repetitive, automatable operational work that scales with service growth and produces no lasting improvement.
Two-Pizza Team	concept	Business Architecture	Amazon's heuristic that a team should be small enough to be fed by two pizzas, and — the substantive part — should own its service end to end.