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
HTTP Method Semantics	concept	REST Design	The safety, idempotency and cacheability guarantees each HTTP method carries, which clients and intermediaries rely on.
Idempotency	concept	Distributed Systems	The property that performing an operation many times has the same effect as performing it once.
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.
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.
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.
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.
Information Hiding	concept	Modularity	Designing module boundaries around the decisions most likely to change, so that a change is contained within one module.
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.
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.
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).
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.
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.
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.
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.
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.
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.
Message Ordering	concept	Messaging & Queues	The guarantee about the sequence in which messages are delivered — normally per-partition or per-group only, and lost the moment consumption is parallelised.
Metric Cardinality	concept	Cardinality	The number of unique label-value combinations on a metric, which multiplies into the number of time series stored and is the primary driver of monitoring cost and failure.
Modularity	concept	Architecture Fundamentals	The degree to which a system is composed of parts that can be understood, changed and replaced independently.
Monolith vs Microservices	concept	Architecture Decision-Making	A trade of deployment independence against distributed-systems complexity, decided by team topology far more often than by technology.
Multi-Cloud	concept	Cloud Architecture	Deliberately running across more than one cloud provider — a decision with a much higher cost than the lock-in it is usually adopted to avoid.
N+1 Resolution DataLoader Problem	concept	GraphQL	The default GraphQL execution behaviour in which each field resolver runs per item, producing one query per row instead of one query per request.
Nines Table	concept	Availability Mathematics	The mapping between availability percentages and permitted downtime, and the cost curve that comes with it.
Noisy Neighbour	concept	Bulkheads & Isolation	One tenant or workload consuming shared resources to the detriment of others sharing the same infrastructure.
Non-Functional Requirement NFR, Quality Attribute	concept	Architecture Fundamentals	A requirement about how well the system must behave rather than what it must do — latency, availability, throughput, security, cost.
Object Storage	concept	Cloud Architecture	Flat, HTTP-addressable storage for immutable blobs with rich metadata — effectively unlimited, cheap, and not a filesystem.
Object-Level Authorization BOLA, IDOR	concept	Authorization	Checking that the caller is entitled to the specific record they requested, not merely that they may call the endpoint.
Observability	concept	Observability	The property of being able to answer new questions about a system's internal state from its external outputs, without shipping new code.
Offset Management	concept	Event Streaming	How a consumer records its position in a stream, and the decision that determines whether processing is at-least-once or at-most-once.
OLTP vs OLAP	concept	Data Warehousing	Two workload shapes with opposite requirements — many small indexed transactions versus few large scans and aggregations — which is why they belong in different stores.
Operational vs Analytical Store	concept	Polyglot Persistence	The separation between the store serving the application's transactions and the one serving reporting and analysis, and the mechanism connecting them.
PACELC	concept	CAP & PACELC	An extension of CAP that also describes the normal case — if Partitioned choose Availability or Consistency, Else choose Latency or Consistency.
Parallelism and Concurrency	concept	Concurrency	The distinction between structuring work so it can make progress independently and actually executing work simultaneously on multiple cores.
Partial Index Filtered Index	concept	Indexing	An index built over only the rows matching a predicate, so it is far smaller and cheaper to maintain than a full index.
Partition Assignment	concept	Competing Consumers	The mapping of partitions to consumer instances that determines parallelism, ordering guarantees and what happens when the consumer set changes.
Partition Tolerance	concept	CAP & PACELC	The ability to keep operating when the network drops or delays messages between nodes — not a choice, but a property of any system spanning more than one machine.
Path MTU Discovery PMTUD	concept	Network Troubleshooting	The mechanism by which a sender discovers the largest packet size a path supports, and a common cause of connections that establish and then hang.
Pattern Overuse	concept	Design Patterns	Applying a design pattern where the problem it solves does not exist, adding indirection and vocabulary without benefit.
Payload Compression Trade-off	concept	Network Performance Tuning	The exchange of CPU time for reduced transfer time, which is favourable on constrained networks and harmful on fast local ones.
Permission Boundary	concept	Identity & Access Management	A policy limiting the maximum permissions an identity can have, used so that the ability to create roles does not become the ability to grant unlimited privilege.
Personally Identifiable Information PII, Personal Data	concept	Security Architecture	Data relating to an identifiable person — a category far broader than name and address, and the trigger for most regulatory obligation.
Pivot Transaction	concept	Sagas & Compensation	The step in a saga after which the transaction can no longer be cancelled — everything before it is compensatable, everything after it is retriable until it succeeds.
Pod	concept	Kubernetes	The smallest deployable unit in Kubernetes — one or more containers that share a network namespace, storage volumes and a lifecycle, scheduled together on one node.
Point-in-Time Recovery PITR	concept	Backup Strategies	Restoring a database to any moment within a retention window by replaying transaction logs onto a base backup, rather than only to a snapshot boundary.
Port Exhaustion	concept	NAT & Egress	Running out of available source ports for outbound connections through a NAT device, causing new connections to fail while everything appears healthy.
Private Endpoint PrivateLink, VPC Endpoint	concept	Private Connectivity	A private network address inside your VPC that reaches a managed service directly, without traversing the internet or a NAT gateway.
Prompt Injection	concept	AI-Era Architecture	An attack in which text from an untrusted source is interpreted by the model as instructions rather than as data.
Provisioned vs Serverless Capacity	concept	Cloud Databases	Paying for a fixed database size continuously, versus paying for capacity consumed with automatic scaling — a crossover decision driven by duty cycle.
Proxy Buffering	concept	Reverse Proxies	Whether a reverse proxy accumulates a response before forwarding it, which protects the backend from slow clients but breaks streaming.
Purpose Limitation	concept	Privacy Engineering	The principle that personal data collected for one stated purpose may not be used for an unrelated one without a new lawful basis.
Query Plan Execution Plan, EXPLAIN	concept	Data Architecture	The database's chosen strategy for executing a query, and the first thing to look at when one is slow.