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
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.
Message Queue	tool	Distributed Systems	A store that holds messages until a consumer processes them, decoupling producer availability and rate from consumer availability and rate.
Message Router	pattern	Integration Patterns	A component that inspects a message and forwards it to one of several destinations based on its content or headers.
Message Translator	pattern	Integration Patterns	A component converting a message between two systems' formats, so neither has to adopt the other's model.
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.
Microsegmentation	pattern	Zero Trust	Enforcing fine-grained network policy between individual workloads rather than between broad network zones, so a compromise cannot move laterally.
Microservices	pattern	Software Architecture	An architectural style where an application is a set of independently deployable services, each owning its data and aligned to a business capability.
Migration Wave	practice	Cloud Migration	A batch of applications migrated together, sequenced so that dependencies move in a workable order and each wave delivers learning for the next.
Model Context Protocol MCP	protocol	AI-Era Architecture	An open protocol that standardises how AI applications connect to external tools, data sources and prompts.
Model Router	pattern	AI-Era Architecture	Directing each request to a model chosen by the task's difficulty, cost and latency budget, rather than sending everything to the largest model available.
Model Routing	pattern	Model Selection	Directing each request to the cheapest model capable of handling it, rather than sending all traffic to the most capable one.
Model Translation Boundary	pattern	Anti-Corruption Layer	The layer at which an external system's model is converted into your own, preventing its concepts and accidents from spreading into your domain.
Modular Monolith	pattern	Architecture Patterns	A single deployable unit internally partitioned into modules with enforced boundaries, explicit interfaces and no shared internal state.
Modularity	concept	Architecture Fundamentals	The degree to which a system is composed of parts that can be understood, changed and replaced independently.
Module Dependency Enforcement	practice	Modular Monolith	Automated checks that prevent one module from importing another's internals, giving a monolith the boundary discipline of separate services.
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.
Monzo's Microservice Estate	case-study	Software Architecture	Monzo runs a bank on well over a thousand microservices, and the interesting engineering is in the platform and network isolation that makes that number survivable.
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.
Multi-Factor Authentication MFA, 2FA	practice	Authentication	Requiring evidence from more than one category — something you know, have, or are — so a single stolen credential is insufficient.
Multi-Leader Replication Multi-Master, Active-Active Replication	pattern	Replication	Accepting writes at more than one node and replicating between them, which removes the single-primary bottleneck and introduces write conflicts.
Mutual TLS mTLS, Client Certificate Authentication	protocol	TLS & Certificates	TLS in which both ends present certificates, so the server authenticates the client cryptographically rather than by a shared secret.
N+1 and 2N Redundancy	pattern	Redundancy	Provisioning one spare beyond required capacity versus provisioning double, and the failure assumptions each encodes.
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.
NAT Gateway Network Address Translation	tool	Networking	A managed device that lets instances in a private subnet make outbound connections without being reachable inbound.
Negotiation	practice	Architecture Communication	Reaching an agreement that both sides own, by trading on interests rather than arguing positions.
Netflix Open Connect	case-study	Networking	Netflix built its own CDN and placed appliances inside ISP networks, turning the most expensive part of its cost structure into hardware it controls.
Netflix's Recommendation Architecture	case-study	Data Architecture	Netflix splits personalisation into offline, nearline and online layers so that expensive computation happens ahead of time and the request path stays fast.
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.
Normalisation Normal Forms	practice	Relational Modelling	Organising a schema so each fact is stored exactly once, removing the update anomalies that duplication creates.
OAuth 2.0	protocol	Security Architecture	An authorisation framework that lets an application obtain scoped, delegated access to a resource without handling the user's credentials.
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.
Open Table Format Apache Iceberg, Delta Lake, Apache Hudi	protocol	Data Lakes & Lakehouses	A metadata layer over files in object storage that supplies ACID transactions, schema evolution and time travel — the thing that turns a data lake into a lakehouse.
OpenAPI Swagger	tool	API & Integration	A machine-readable specification format for HTTP APIs, from which documentation, clients, servers, mocks and validation can be generated.
OpenID Connect OIDC	protocol	Security Architecture	An identity layer over OAuth 2.0 that adds a signed ID token asserting who the user is and how they authenticated.
OpenTelemetry OTel	tool	OpenTelemetry	A vendor-neutral standard and toolset for generating, collecting and exporting traces, metrics and logs.
Operational Burden Assessment	practice	Managed vs Self-Managed	Quantifying the ongoing engineering effort a self-managed component requires, so it can be compared honestly with a managed service's price.
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.
Optimistic Concurrency Control OCC, Compare-and-Set	pattern	Distributed Locking	Allowing concurrent work without locks and detecting conflict at write time by checking that the underlying version has not changed.
Origin Shield	pattern	Content Delivery Networks	An intermediate caching layer between CDN edge nodes and the origin, so a cache miss at many edges results in one origin request rather than many.
Outbox Pattern Transactional Outbox	pattern	Architecture Patterns	Writing an outgoing message into a table in the same transaction as the business change, and relaying it to the broker separately, so the two cannot diverge.
Outbox Relay	pattern	Outbox	The process that reads pending messages from an outbox table and publishes them to a broker, providing at-least-once delivery with no distributed transaction.
Output Validation Layer	pattern	Guardrails	A deterministic check applied to model output before it is used, treating the model as an untrusted component.
OWASP Top Ten	practice	Security Architecture	A periodically updated consensus list of the most critical web application security risks, useful as a design-review checklist.
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.
Page and Ticket Routing	practice	Alerting	Deciding for each monitored condition whether it warrants immediate human interruption or asynchronous handling, and enforcing the distinction.
Parallel Run	practice	Legacy Modernization	Running the old and new systems side by side on the same inputs and comparing outputs, before the new one is trusted.
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.
Partner Onboarding	practice	Partner & B2B Integration	The repeatable process by which an external organisation is connected, tested and moved to production — and a common hidden bottleneck.
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.
Pattern Recognition	practice	Meta-Skills	Recognising that a novel-looking problem is an instance of one you have seen before, and knowing which parts of the previous solution transfer.