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
Abstraction	concept	Architecture Fundamentals	Exposing what a component does while hiding how it does it, so callers depend on the contract rather than the mechanism.
Active-Active vs Active-Passive	concept	Multi-Region Architecture	Whether all regions serve traffic simultaneously, or one serves while another waits to take over — a choice about which failure mode you would rather have.
Agent Loop	concept	Agent Architectures	The cycle in which a model observes state, selects an action, executes a tool and observes the result, repeating until a goal or a limit is reached.
Alert Fatigue	concept	Observability	The desensitisation that follows from alerts that are frequent, non-actionable, or not tied to user impact — after which real alerts are missed too.
Amdahl's Law	concept	Profiling & Optimisation	The limit on speedup from optimising or parallelising part of a system, set by the proportion of work that remains unchanged.
Anycast	concept	Networking	Advertising the same IP address from many locations, so the network routes each client to the topologically nearest one.
Approximate Nearest Neighbour Index ANN	concept	Vector Databases	An index that trades exactness for speed when finding similar vectors, making large-scale semantic search feasible.
Architect Archetypes	concept	Architecture Roles	The distinct scopes of architecture practice — enterprise, solution, domain and application — and the different skills and decision rights each carries.
Architectural Debt	concept	Evolutionary Architecture	Structural compromises that increase the cost of all future change, distinguished from code-level debt by being expensive and slow to repay.
Architectural Driver	concept	Architecture Fundamentals	The small subset of requirements and constraints that actually shape the structure of the system.
Architecturally Significant Requirement ASR	concept	Architectural Drivers	A requirement whose satisfaction demands a structural decision, as opposed to one that can be met by any reasonable implementation.
Architecture Sinkhole	concept	Layered Architecture	A request that passes through every layer of a layered architecture without any layer adding logic, indicating that the layering is pure overhead for that path.
Architecture Style	concept	Architecture Fundamentals	A named, coarse-grained way of organising a whole system, as distinct from a pattern that solves one recurring problem inside it.
Architecture Viewpoint	concept	Architecture Documentation	A perspective on a system tailored to the concerns of a particular audience, recognising that no single diagram serves everyone.
At-Least-Once Delivery	concept	Messaging & Queues	The guarantee that a message will be delivered, possibly more than once — the practical default in every distributed messaging system.
Atomic Commit Protocol	concept	Distributed Transactions	Any protocol ensuring that several participants reach the same decision to commit or abort — and a problem provably unsolvable with certainty in an asynchronous system with failures.
Attack Surface	concept	Threat Modelling	The complete set of points where an untrusted actor can interact with a system — and the quantity that reduction genuinely reduces risk.
Auditability	concept	Security Architecture	The ability to reconstruct who did what, to which resource, when, and from where — reliably enough to be relied upon after the fact.
Authentication AuthN	concept	Security Architecture	Establishing who a principal is, to a defined level of confidence.
Authorization AuthZ	concept	Security Architecture	Deciding whether an authenticated principal may perform a specific action on a specific resource.
Availability Arithmetic	concept	Availability Mathematics	Multiplying dependency availabilities in series and combining redundant components in parallel to derive a system's achievable availability.
Availability Calculation	concept	Reliability & Resilience	Deriving a system's availability from its components, remembering that dependencies in series multiply.
Availability Zone AZ	concept	Cloud Architecture	One or more physically separate data centres inside a cloud region, with independent power, cooling and network, connected by low-latency links.
Backpressure	concept	Distributed Systems	A mechanism by which a component under load tells its callers to slow down, rather than accepting work it cannot complete.
Backward Compatibility	concept	API & Integration	The property that a new version of a producer continues to work with clients written against the old version.
Bandwidth-Delay Product	concept	Network Performance	Bandwidth multiplied by round-trip time — the amount of data that must be in flight to keep a link fully utilised.
Binary Serialisation	concept	Message Formats	Encoding messages compactly using a schema rather than as self-describing text, trading readability for size and parse speed.
Blast Radius	concept	Cloud Architecture	The set of things that break, or become reachable, when one component fails or is compromised.
Block Storage Persistent Disk, EBS	concept	Cloud Storage	A virtual disk attached to one instance at a time, presented as raw blocks and formatted with a filesystem — the storage databases and stateful workloads run on.
Bottleneck	concept	Bottleneck Analysis	The single resource that limits system throughput, such that improving anything else produces no gain.
Build vs Buy	concept	Architecture Decision-Making	The choice between developing a capability in-house and acquiring it, decided on differentiation and total cost rather than on feature lists.
Burstable Instance T-series, B-series	concept	Compute Models	An instance that provides a low baseline CPU allocation and accrues credits while idle, spendable for short periods of full performance.
Business Capability	concept	Business Architecture	What a business does, expressed stably and independently of how it currently does it or who is responsible.
Byzantine Fault	concept	Failure Modes	A failure in which a component behaves arbitrarily or deceptively — returning wrong results rather than stopping — as distinct from simply crashing.
Cache Hit Ratio Economics	concept	Caching for Performance	The non-linear relationship between cache hit rate and backend load, which determines whether a cache improvement is worth making.
Cache Invalidation	concept	Data Architecture	The problem of removing or refreshing cached data when the underlying source changes, and the reason caching is harder than it looks.
Cache Penetration	concept	Cache Invalidation	Repeated lookups for keys that do not exist, which miss the cache every time by definition and pass straight through to the store.
Cache Stampede Dog-piling, Thundering Herd on Cache	concept	Cache Invalidation	Many concurrent requests missing on the same expired key and all recomputing it simultaneously, converting one expiry into a load spike.
CAP Theorem Brewer's Theorem	concept	Distributed Systems	During a network partition a distributed system must choose between consistency and availability; it cannot have both.
Capability Model	concept	Reference Models	A structured map of what a business does, independent of how it is organised or which systems support it, used to align technology investment with function.
Cardinality	concept	Observability	The number of distinct time series produced by a metric, which is the product of the distinct values of all its labels — and the main driver of monitoring cost.
Cardinality Estimation	concept	Query Optimisation	The planner's prediction of how many rows each step of a query will produce — the input that determines every other choice it makes.
Cascading Timeout	concept	Timeouts & Deadlines	The effect of independently-chosen per-hop timeouts summing to a total far longer than any caller is willing to wait.
Causal Consistency	concept	Consistency Models	A model guaranteeing that operations which causally depend on one another are seen in the same order everywhere, while concurrent operations may be seen in any order.
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 Router	concept	Cell-Based Architecture	The thin component that maps a request to its cell, and which is the one shared dependency a cell-based architecture must keep minimal.
Centralisation Trade-off	concept	Centralised vs Distributed	The exchange between consistency and control gained by centralising a capability and the autonomy and speed retained by distributing it.
Certificate Chain Chain of Trust	concept	TLS & Certificates	The sequence from a server's certificate through one or more intermediate CAs to a root the client already trusts.
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.
Compatibility Mode	concept	Schema Registry	The registry setting that defines which schema changes are permitted — backward, forward, full, or none — and therefore what upgrade order is safe.
Complexity Budget	concept	Reliability vs Complexity	The idea that an organisation can operate only a bounded amount of complexity, so each resilience mechanism must justify its share.
Concurrency	concept	Performance & Capacity	The number of operations in progress at once — distinct from parallelism, which is how many are literally executing simultaneously.
Configuration Drift	concept	Infrastructure as Code	Divergence between the infrastructure described in code and the infrastructure actually running, usually caused by manual changes.
Connection Draining Deregistration Delay	concept	Load Balancing	The period during which a load balancer stops sending new requests to an instance while allowing in-flight ones to complete before it is removed.
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.
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.