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

681 terms shown.

Term	Kind	Topic	What it is
HTTP Method Semantics	concept	REST Design	The safety, idempotency and cacheability guarantees each HTTP method carries, which clients and intermediaries rely on.
HTTP/2 Multiplexing	protocol	HTTP/1.1, HTTP/2 & HTTP/3	Carrying many concurrent request/response streams over a single TCP connection, removing the need for multiple connections per origin.
Human in the Loop HITL	pattern	AI-Era Architecture	Requiring human review or approval at a defined point in an automated flow, chosen by the reversibility and cost of the action.
Idempotency	concept	Distributed Systems	The property that performing an operation many times has the same effect as performing it once.
Idempotency Key	pattern	API & Integration	A client-generated unique value sent with a request so the server can recognise a retry and return the original result instead of acting twice.
Idempotency Scope	concept	Idempotency Keys	The boundary within which an idempotency key is unique and meaningful — per account, per endpoint, or global — and the retention window it lives for.
Idempotency Token Store	pattern	Idempotency	The durable record of which idempotency keys have been seen and what each one returned, and the component that decides whether the guarantee is real.
Idempotent Pipeline	practice	ETL & ELT	A pipeline whose task can be re-run for the same input window any number of times and produce the same result.
Identity and Access Management IAM	concept	Security Architecture	The system of record for principals, credentials and permissions, and the policy engine that decides what each principal may do.
Image Registry	tool	Containers	The store from which container images are pulled, and an under-appreciated availability and security dependency of every deployment and every autoscale event.
Immutable Backup Object Lock, WORM	pattern	Backup Strategies	A backup that cannot be modified or deleted for a defined retention period, even by an administrator — the control that makes backups survive ransomware and insider error.
Incident Command Incident Command System, ICS	practice	Reliability & Resilience	Assigning explicit roles during an incident — commander, operations lead, communications lead, scribe — so coordination does not compete with diagnosis.
Incident Severity Levels	practice	Incident Management	A small, agreed scale of incident severity that determines response, escalation and communication without requiring debate during the event.
Independent Deployability	concept	Microservices	The property that a service can be released to production without coordinated release of any other, which is the defining benefit of microservices.
Index Selectivity	metric	Indexing	The fraction of rows a predicate eliminates — the property that determines whether an index is worth using at all.
Indexing Strategy	practice	Data Architecture	Choosing the set of indexes a table carries by working backwards from its actual queries, and accepting the write cost that each one adds.
Indirect Prompt Injection	concept	Prompt Injection Defence	An attack in which malicious instructions are placed in content the model will later retrieve, rather than typed by the user.
Inference Request Path	concept	LLM Application Architecture	The sequence of stages an LLM application request passes through, each with distinct latency, cost and failure characteristics.
Inference Telemetry	practice	AI Observability	Recording the full context of each model interaction — inputs, outputs, tokens, latency, model version and evaluation scores — so quality and cost can be investigated.
Information Hiding	concept	Modularity	Designing module boundaries around the decisions most likely to change, so that a change is contained within one module.
Infrastructure as Code IaC	practice	Cloud Architecture	Defining infrastructure in version-controlled declarative files that a tool reconciles against the real environment.
Instagram's Early Scaling	case-study	Architecture Fundamentals	Instagram reached tens of millions of users on Django and PostgreSQL with a handful of engineers, by deliberately choosing boring technology and doing the simple thing first.
Instance Family	concept	Compute Models	A group of instance types sharing a resource profile — general purpose, compute optimised, memory optimised, storage optimised, accelerated — chosen by which resource the workload actually exhausts first.
Inverse Conway Manoeuvre	practice	Conway's Law	Deliberately structuring teams to match the architecture you want, on the basis that the system will come to mirror the organisation regardless.
Join Strategies	concept	Query Optimisation	The three ways a database combines two row sets — nested loop, hash join and merge join — and the conditions under which each is correct.
JSON Web Token JWT	protocol	Security Architecture	A signed, self-contained token carrying claims, which a service can validate locally without calling the issuer.
JWKS JSON Web Key Set	protocol	Tokens & JWTs	A published endpoint listing an issuer's current public keys, allowing resource servers to validate token signatures without a shared secret and to survive key rotation.
Key Rotation	practice	Key Management	Periodically replacing a cryptographic key with a new one while retaining the old for decrypting existing data, so exposure from any single key is bounded.
Kubernetes K8s	tool	Cloud Architecture	A container orchestrator that continuously reconciles the running state of a cluster towards a declared desired state.
Kubernetes Operator	pattern	Kubernetes	A custom controller that encodes operational knowledge for a specific application, reconciling a custom resource towards a desired state the same way built-in controllers do.
Landing Zone	practice	Cloud Architecture	A pre-configured, governed cloud environment — accounts, networking, identity, logging, guardrails — into which workloads can be deployed safely.
Last Responsible Moment	concept	Evolutionary Architecture	Deferring a decision until the point beyond which delaying it would cost more than deciding now, in order to decide with the most information available.
Latency Budget Decomposition	practice	Latency	Allocating a total response-time target across the components of a request path, so each layer has an explicit share and overruns are attributable.
Layer 4 vs Layer 7 Load Balancing	concept	Networking	Balancing on connection metadata (IP and port) versus on the content of the request (path, host, headers).
Layered Architecture N-Tier	pattern	Architecture Patterns	Organising code into horizontal layers — presentation, application, domain, data — where each layer may only call the one beneath it.
Leader Election	pattern	Distributed Systems	The process by which a group of nodes agrees which one of them is currently in charge of a task that must not run twice.
Leaky Abstraction	concept	Abstraction & Encapsulation	An abstraction whose underlying implementation details become visible or consequential, requiring users to understand what it was meant to hide.
Lease	concept	Leader Election	Time-bounded leadership or ownership that must be renewed before it expires, so a leader that becomes unreachable automatically relinquishes its role.
Least Privilege	concept	Security Architecture	Granting each identity only the permissions it needs, for only as long as it needs them.
Linearizability Atomic Consistency, Strong Consistency	concept	Consistency Models	The strongest single-object guarantee — every operation appears to take effect instantaneously at some point between its call and its return.
LinkedIn and the Origin of Kafka	case-study	API & Integration	Kafka was built to replace point-to-point data integration between many systems with a single durable log that any system could publish to and any number could read.
Little's Law	concept	Performance & Capacity	In a stable system, the average number of items in it equals the arrival rate times the average time each spends in it — L = λW.
Little's Law Applied to Pools	practice	Connection Pooling	Using L = λW to size connection and thread pools from measured throughput and latency rather than from a default.
LLM Evaluation Evals	practice	AI-Era Architecture	A repeatable measurement of whether an AI system's outputs are good enough, on cases that reflect the actual task.
LLM-as-Judge	practice	LLM Evaluation	Using a model to score another model's output against a rubric, providing scalable evaluation where exact-match assertions do not apply.
Load Balancing Algorithm	concept	Layer 4 vs Layer 7	The rule deciding which backend receives a request — round robin, least connections, least response time, or hash-based.
Load Shedding	pattern	Distributed Systems	Deliberately rejecting a portion of incoming work during overload so that the remainder can be served correctly.
Load Testing	practice	Performance & Capacity	Driving a system with realistic traffic at a target volume to verify it meets its performance targets before real users do.
Lock Lease Expiry	concept	Distributed Locking	The timeout on a distributed lock that prevents a crashed holder deadlocking the system — and the source of the pattern's hardest failure mode.
Log Compaction	concept	Event Streaming	A retention policy that keeps only the most recent value for each key rather than deleting by age, so the log becomes a durable snapshot of current state.
Log Level Discipline	practice	Logging	Consistent semantics for log severity so that levels can be used for routing, alerting and cost control.
Log Retention Tiering	practice	Log Management	Storing log data at different resolutions, costs and access latencies according to how old it is and how likely it is to be queried.
Log Schema Consistency	practice	Structured Logging	Enforcing the same field names, types and semantics for structured log records across every service, so cross-service queries are possible.
Log-Based CDC	pattern	Change Data Capture	Capturing changes by reading the database's own write-ahead log, which sees every change with no load on the source and no application involvement.
Managed Service	concept	Cloud Architecture	A capability the provider operates — provisioning, patching, backup, scaling and failover — leaving you the configuration and the data.
Managed Service Upgrade Window	concept	Managed Services	The period during which a provider may apply patches or version upgrades to a managed service, usually involving a failover or brief unavailability.
Managed vs Self-Managed	concept	Architecture Decision-Making	Trading control, portability and unit cost against the operational burden of running the thing yourself.
Mass Assignment Auto-Binding, Over-Posting	concept	Secure API Design	A vulnerability where a request body is bound directly to an internal object, allowing a caller to set fields the API never intended to expose.
Materialized View	pattern	Data Architecture	A precomputed, stored result of a query, refreshed on a schedule or from a change stream, read instead of recomputing.
Mesh Control Plane	concept	Service Mesh	The component that configures and coordinates a service mesh's data plane proxies, distributing policy, identity and routing rules.