Terminology

454 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 areas454 Architecture Fundamentals16 Distributed Systems73 Data Architecture71 Cloud Architecture55 Networking13 API & Integration Architecture17 Reliability & Resilience16 Observability14 Performance & Capacity Engineering13 Security Architecture50 Cost Architecture & FinOps12 Business Architecture9 Architecture Communication8 Enterprise Architecture8 Legacy Modernization11 AI-Era Architecture15 Software Architecture & Engineering19 Architecture Patterns15 Architecture Decision-Making11 The Architect's Meta-Skills8

Kind Any concept166 practice107 pattern93 case-study26 tool26 protocol22 metric14

454 terms shown.

Term	Kind	Topic	What it is
Game Day	practice	Reliability & Resilience	A scheduled exercise in which a failure is deliberately introduced and the team responds as though it were real, to test the system and the response together.
Global Traffic Management GSLB, Global Load Balancing	tool	Multi-Region Architecture	The layer that decides which region a given user reaches, using DNS, anycast or an edge network, and that performs regional failover.
Golden Signals	metric	Observability	The four measurements that cover most of what matters for a request-driven service: latency, traffic, errors and saturation.
Google Maps and Planetary-Scale Spatial Serving	case-study	Performance & Capacity	Map serving is fast because almost nothing is computed on request — the world is precomputed into a pyramid of tiles, and space is indexed onto a one-dimensional curve.
Graceful Degradation	practice	Distributed Systems	Continuing to deliver reduced but useful function when a dependency fails, instead of failing the whole request.
Graph Database	tool	NoSQL Stores	A store whose first-class citizens are nodes and the relationships between them, making multi-hop traversal cheap.
GraphQL	protocol	API & Integration	A query language and runtime where the client specifies exactly which fields it needs, against a typed schema, usually via a single endpoint.
Grey Failure Partial Failure, Fail-Slow	concept	Failure Modes	A component that is degraded rather than down — slow, intermittently erroring, or failing for a subset of operations — which defeats health checks built for binary states.
gRPC	protocol	API & Integration	A contract-first RPC framework using Protocol Buffers over HTTP/2, with generated clients and servers and first-class streaming.
Guardrail	pattern	AI-Era Architecture	A deterministic check applied to a model's input or output, enforcing rules that cannot be left to the model itself.
Half-Open State	concept	Circuit Breakers	The circuit breaker state that allows a limited number of trial requests through to test whether a failed dependency has recovered.
Hardware Security Module HSM	tool	Key Management	A tamper-resistant device that generates and stores keys and performs cryptographic operations without the key material ever being extractable.
Harvest and Yield	concept	CAP & PACELC	A refinement of CAP that treats availability as a continuum — yield is the fraction of requests answered, harvest is the fraction of data reflected in an answer.
Health Check	practice	Observability	An endpoint the platform polls to decide whether an instance should be restarted or should receive traffic — two different questions needing two different checks.
Hedged Request Request Hedging, Tied Request	pattern	Performance & Capacity	Sending a duplicate of a request to a second replica after a short delay and using whichever response returns first, to cut tail latency.
Hexagonal Architecture Ports and Adapters	pattern	Architecture Patterns	Putting the domain at the centre and letting everything external — UI, database, queues — attach through ports implemented by replaceable adapters.
Horizontal vs Vertical Scaling Scale Out vs Scale Up	concept	Performance & Capacity	Adding more machines versus making one machine bigger — and the fact that vertical is underrated for stateful tiers.
Hot Partition Hot Shard, Hot Key	concept	Partitioning & Sharding	One partition receiving disproportionate traffic, so the system saturates at a fraction of its aggregate capacity.
Hot, Warm and Cold Data	concept	Data Lifecycle & Retention	Classifying data by how frequently and how urgently it is accessed, so each tier can be stored on media priced for that access pattern.
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 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.
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.
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.
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.
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.
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.
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-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.