Terminology

384 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 areas384 Architecture Fundamentals16 Distributed Systems73 Data Architecture71 Cloud Architecture17 Networking13 API & Integration Architecture17 Reliability & Resilience16 Observability14 Performance & Capacity Engineering13 Security Architecture18 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 concept136 practice90 pattern81 case-study26 protocol19 tool19 metric13

384 terms shown.

Term	Kind	Topic	What it is
CDC Initial Snapshot	concept	Change Data Capture	The consistent full copy taken when a CDC pipeline starts, before streaming begins — and the step that determines whether the target is correct.
Cell Isolation	pattern	Bulkheads & Isolation	Bulkheading at the level of a complete system copy, so that any failure — including ones nobody predicted — is contained to the customers assigned to one cell.
Cell-Based Architecture Cellular Architecture	pattern	Architecture Patterns	Partitioning a service into complete, independent copies of itself, each serving a subset of customers, so a failure is bounded to one cell.
Change Data Capture CDC	pattern	Data Architecture	Publishing a stream of a database's row-level changes by reading its replication log, without modifying the application that owns it.
Chaos Engineering	practice	Reliability & Resilience	Deliberately injecting failure into a system to discover, before an incident does, which of your resilience assumptions are false.
Chargeback and Showback	practice	Cost & FinOps	Attributing cloud cost to the teams that generate it — either informationally (showback) or by moving it onto their budget (chargeback).
CI/CD Continuous Integration, Continuous Delivery	practice	Software Architecture	Merging work continuously into a shared trunk with automated verification, and keeping every commit in a state that could be released.
Circuit Breaker	pattern	Distributed Systems	A proxy that stops calling a failing dependency after a failure threshold, failing fast instead, and periodically tests whether it has recovered.
Clean Architecture	pattern	Software Architecture	Concentric layers with a strict dependency rule — source code dependencies point only inwards, towards higher-level policy.
Client-Side Discovery	pattern	Service Discovery	The caller queries the registry itself and chooses an instance, rather than sending to a stable address that something else resolves.
Cloud Pricing Models	concept	Cost & FinOps	The purchase options for cloud compute — on-demand, committed use, and spot — which differ by up to 90% for identical hardware.
Cognitive Load	concept	Software Architecture	The total amount a team must hold in its head to work effectively, and a real constraint on how many services or domains one team can own.
Cohesion	concept	Architecture Fundamentals	The degree to which everything inside one component belongs together and changes for the same reason.
Compensating Transaction	pattern	Sagas & Compensation	A business operation that semantically undoes a previously committed step — not a rollback, because the original effect was visible and may not be fully reversible.
Competing Consumers	pattern	Architecture Patterns	Multiple identical consumers reading from one queue, so throughput scales with consumer count and work is distributed automatically.
Compliance Framework SOC 2, ISO 27001, PCI DSS	practice	Security Architecture	A published set of control requirements an organisation is assessed against, which turns security posture into evidence somebody else will check.
Concurrency	concept	Performance & Capacity	The number of operations in progress at once — distinct from parallelism, which is how many are literally executing simultaneously.
Connection Pool	concept	Performance & Capacity	A fixed set of reusable database connections shared by an application's requests, and one of the most common hidden capacity ceilings.
Consistent Hashing	concept	Distributed Systems	A hashing scheme where adding or removing a node remaps only a small fraction of keys, instead of nearly all of them.
Consistent Prefix Read	concept	Consistency Models	A guarantee that if a sequence of writes happens in a given order, a reader sees a prefix of that sequence — never an out-of-order subset.
Constraint Thinking	practice	Meta-Skills	Designing for the budget, timeline, skills, regulations and existing estate that actually exist, rather than for the ones a textbook assumes.
Consumer Group	concept	Event Streaming	A set of consumers that cooperatively read one stream, with each partition assigned to exactly one member, so the group collectively processes every message once.
Content Delivery Network CDN	tool	Networking	A geographically distributed cache that serves content from a location near the user instead of from the origin.
Context Window	concept	AI-Era Architecture	The maximum number of tokens a model can attend to in one request, holding the system prompt, history, retrieved context, tools and the answer.
Contract Testing	practice	API & Integration	Verifying that a provider satisfies the expectations each of its consumers actually relies on, without running all the services together.
Control Plane and Data Plane	concept	Cloud Architecture	The separation between the machinery that makes changes to a system and the machinery that serves its traffic.
Conway's Law	concept	Architecture Fundamentals	Systems tend to mirror the communication structure of the organisation that builds them.
Correlation ID	practice	Observability	A single identifier attached to one logical operation and included in every log line it produces, anywhere in the system.
Cost per Request	metric	Cost & FinOps	The fully-loaded infrastructure cost of serving one request, and the unit that makes architectural cost decisions comparable.
Cost vs Reliability Trade-off	concept	Cost & FinOps	The non-linear relationship between availability and spend, which makes each additional nine roughly an order of magnitude more expensive.
Coupling	concept	Architecture Fundamentals	The degree to which one component must know about, or change alongside, another.
Covering Index Index-Only Scan	concept	Indexing	An index that contains every column a query needs, so the query is answered from the index without reading the table at all.
CQRS Command Query Responsibility Segregation	pattern	Data Architecture	Separating the model used to change state from the model used to read it, so each can be optimised independently.
Credit-Based Flow Control	protocol	Backpressure & Flow Control	A scheme where a receiver grants the sender a budget of bytes or messages it may transmit, replenished as the receiver consumes.
Crypto-Shredding Cryptographic Erasure	pattern	Data Lifecycle & Retention	Encrypting each subject's data with its own key and destroying that key to render the data permanently unreadable, achieving deletion without deleting.
Data Catalog	tool	Data Governance	A searchable inventory of datasets with their schema, owner, meaning, freshness, quality and classification.
Data Contract	practice	Data Governance	An explicit, versioned, enforced agreement between a data producer and its consumers about schema, semantics, quality and change policy.
Data Lakehouse	concept	Data Architecture	A pattern that puts warehouse-style transactions, schema and governance on top of cheap open-format object storage.
Data Lineage	practice	Data Governance	A record of where each dataset came from, what transformed it, and what depends on it — traced at table and ideally column level.
Data Mesh	concept	Data Architecture	An organisational approach that gives domain teams ownership of their analytical data as a product, with a self-serve platform and federated governance.
Data Residency Data Sovereignty	concept	Security Architecture	A requirement that specific data be stored and sometimes processed only within a defined geography.
Data Retention Policy	practice	Data Architecture	A defined rule for how long each class of data is kept, where, and what happens at the end of it.
Data-Flow Diagram DFD	practice	Architecture Communication	A diagram of how data moves between processes, stores and external entities, with trust boundaries drawn on it.
Database Index	concept	Data Architecture	A secondary structure that lets the engine find rows without scanning, trading write cost and storage for read speed.
Database per Service	pattern	Polyglot Persistence	Each service owning its own datastore, with no other service reading or writing it directly.
Dead Letter Queue DLQ	pattern	API & Integration	A separate queue that receives messages which could not be processed after a set number of attempts, so they neither block the consumer nor disappear.
Deadline Exceeded	concept	Timeouts & Deadlines	The error returned when a request's overall budget expires — semantically distinct from a per-hop timeout, and a signal that must not be retried blindly.
Decision-Making Under Uncertainty	practice	Meta-Skills	Choosing well when the information is incomplete — by bounding the downside and buying information, rather than by waiting for certainty.
Delivery vs Maintainability Short-term Delivery vs Long-term Maintainability, Speed vs Quality	concept	Architecture Decision-Making	Choosing where to take deliberate shortcuts, based on which kinds of debt are cheap to repay and which compound.
Denormalisation	practice	Data Architecture	Deliberately duplicating data across records to make reads cheap, accepting the write-time cost of keeping copies in step.
Disaster Recovery DR	practice	Reliability & Resilience	The plan and capability for restoring service after an event that takes out a whole site, region or system.
Discord's Message Store Migrations	case-study	Data Architecture	Discord moved from MongoDB to Cassandra to ScyllaDB as message volume grew from millions to trillions, each time for a specific and different reason.
Distributed Tracing	tool	Observability	Following one logical request across every service it touches by propagating a shared trace identifier and recording timed spans.
DNS Domain Name System	protocol	Networking	The distributed directory that resolves names to addresses, and a surprisingly load-bearing part of most architectures.
Document Store	tool	NoSQL Stores	A store that keeps semi-structured documents — typically JSON — retrievable by key and queryable by their contents.
Domain-Driven Design DDD	practice	Software Architecture	Modelling software around the business domain, with boundaries drawn where the language of the business changes.
DORA Metrics Four Key Metrics	metric	Software Architecture	Four measures of software delivery performance — deployment frequency, lead time for change, change failure rate, and time to restore service.
Dropbox's Move Off S3 Magic Pocket	case-study	Cost & FinOps	Dropbox moved the majority of its file storage off Amazon S3 onto custom infrastructure, reporting savings that its S-1 filing put at roughly $75 million over two years.
Dual Write	pattern	Data Migration Strategies	Writing the same change to both the old and new stores during a migration, and the reconciliation that makes it trustworthy.
eBay's Architectural Generations	case-study	Legacy Modernization	eBay rewrote its core platform several times across its first decade, each time because the previous generation had hit a limit that could not be tuned away.