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Terminology

2205 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 areas2205 Architecture Fundamentals77 Distributed Systems107 Data Architecture110 Cloud Architecture94 Networking88 API & Integration Architecture82 Reliability & Resilience75 Observability70 Performance & Capacity Engineering72 Security Architecture86 Cost Architecture & FinOps71 Business Architecture67 Architecture Communication67 Enterprise Architecture66 Legacy Modernization71 AI-Era Architecture69 Software Architecture & Engineering71 Architecture Patterns71 Architecture Decision-Making63 The Architect's Meta-Skills61 Delivery & Release Engineering66 Platform Engineering & Developer Experience70 Testing & Quality Architecture66 Data Platform Architecture64 Streaming & Real-Time Data69 Data Governance & Semantics69 Frontend & Experience Architecture66 Edge, Mobile & IoT68 Regulatory & Data Protection Architecture65 Assurance, Audit & Model Risk64
Kind Any concept794 practice734 pattern368 metric125 case-study77 tool62 protocol45

794 terms shown.

Term Kind Topic What it is
Join Replay Misalignment One-Sided Replay, Split-Watermark Join concept Streaming Joins The failure that follows from replaying one input of a stateful join while the other stays live - event times no longer overlap, window state is never cleaned, and the output is wrong in both directions with n…
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.
Keep-Lit Capacity Floor Keep-the-Lights-On Floor, Legacy Demand Floor, Maintenance Floor concept Rebuild vs Re-architect The share of engineering capacity a legacy system consumes no matter what else is planned, which decides whether a rebuild is funded at all - and which a change freeze defers rather than removes.
Key Skew concept Partition Keys & Ordering An uneven distribution of records across partitions, which caps throughput at the busiest partition regardless of how many exist.
Kubernetes Resource Requests and Limits concept Kubernetes The declared minimum a container is guaranteed and the maximum it may consume, which drive scheduling, eviction and throttling in ways that are easy to get wrong.
KV Cache Attention Cache, Key-Value Cache, Prefix Cache concept LLM Application Architecture The per-session key and value tensors a transformer must hold in GPU memory to generate each subsequent token - the resource that limits concurrent sessions, and whose reuse across turns is the difference betw…
Lakehouse concept Warehouse, Lake & Lakehouse An architecture combining a lake's cheap open storage with a warehouse's transactions, schema enforcement and query performance, through a table format layer.
Lateral Movement concept Zero Trust An attacker's progression from an initial foothold to more valuable systems, which is what turns a minor compromise into a breach.
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).
Layer Contract Guarantee Not Position, Medallion Discipline concept Medallion Architecture The rule that a data layer is defined by the guarantee it makes to consumers, not by its position in a naming convention - without which the layers convey nothing.
Leading and Lagging Indicator concept Business KPIs The distinction between a measure that predicts an outcome and one that confirms it after the fact, determining whether a metric can be acted on.
Leading Health Signal In-Band Invariant Signal, Detection-Latency Gate concept Deployment Strategies A rollout gate input whose latency is shorter than the damage it indicates - the property that decides whether any bake time can catch a defect, as distinct from how much traffic the rollout exposes.
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.
Leaky Abstraction Cost concept Abstraction Level Choice What a consumer pays when a platform abstraction hides a mechanism they must nonetheless understand to diagnose or tune it.
Learning Debt concept Continuous Learning The accumulating gap between an architect's knowledge and the current state of the field, which compounds silently because nothing forces its repayment.
Lease concept Distributed Locking A lock with an expiry, granting exclusive rights for a bounded time so that a crashed holder cannot block the system forever.
Least Privilege concept Security Architecture Granting each identity only the permissions it needs, for only as long as it needs them.
Legitimate Divergence Expected Parallel-Run Difference, Correct-on-Both-Sides Delta concept Warehouse Migration The class of differences between an old and a new analytical platform that are correct on both sides, which a parallel run must classify and budget for rather than investigate as defects.
Licence Costs concept Licence & Vendor Costs Software licensing whose pricing model frequently constrains architecture more than its technical characteristics do.
Licence Metric Risk concept Licence & Vendor Costs The exposure created when a software licence is priced on a unit that cloud architecture changes unpredictably, such as cores, sockets or instances.
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.
Liveness vs Readiness concept Health Checks Two distinct questions - should this process be restarted, and should it receive new work - which must be answered by different checks with opposite sensitivities.
Load Balancer Types concept Layer 4 vs Layer 7 Layer 4 against layer 7, the algorithms that distribute requests, and why "least connections" is usually better than round robin.
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 CDC to Stream Retaining only the most recent value for each key in a topic, so the log becomes a durable snapshot of current state rather than a bounded window of history.
Log Schema Drift Field Type Drift, Telemetry Schema Breakage concept Structured Logging The silent breakage of dashboards and alerts when a service changes the name, type or nesting of a structured log field, producing empty results rather than errors.
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 Calendar Provider Support Lifecycle Exposure, Vendor Upgrade Clock concept Replatforming The obligation, transferred to the provider at replatform time, to upgrade before a published end-of-standard-support date, which converts an indefinitely deferrable version upgrade into a dated one the team d…
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 Services concept Managed Services Paying a provider to operate a component — usually the right default, with a small number of genuine reasons to self-manage.
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 Formats concept Message Formats JSON, Protobuf, Avro and the rest — chosen by who the consumer is and how the schema will evolve.
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 Overhead Budget concept Constrained Protocols The proportion of each transmission spent on protocol rather than payload, which on a metered or battery-powered link determines the running cost.
Metadata Read Amplification Planning-Time Amplification, Manifest Read Blow-Up concept Open Table Formats The number of small sequential metadata requests a table format issues before reading any data, which grows with file history and turns a modest storage slowdown into a large query slowdown.
Metastable Failure Congestive Collapse, Death Spiral concept Failure Modes A failure state that sustains itself after the original trigger is gone, because the system's own recovery behaviour generates the load keeping it down.
Metric Cardinality concept Cardinality The number of unique label combinations on a metric, which determines the number of time series stored and is the main driver of monitoring cost and failure.
Metric Staleness Staleness Marker, Stale Series concept Metrics The rules deciding how long a time series keeps answering queries after it stops being written - which determines whether a dead process's last value is served as current, and whether an alert on a vanished se…
Metric Temporality Delta Temporality, Cumulative Temporality concept OpenTelemetry Whether a reported metric point carries a running total since a start time or only the change during one interval - the choice that decides whether process restarts or duplicate deliveries are what corrupts yo…
Metrics concept Metrics Cheap pre-aggregated numeric time series — excellent for knowing something is wrong, structurally unable to tell you which request.
Minimum Necessary Access concept Healthcare Data Protection Restricting each user to the health information required for their specific role and, in the strong form, to the patients they are actually treating.
Minimum Storage Duration Charge Early Deletion Fee, Minimum Billable Duration concept Storage Costs The contractual floor on how long an object in a cheaper storage class is billed for, which converts deletions and extra lifecycle hops inside that window into charges rather than savings.
ML Platform concept ML Platform The infrastructure that makes machine learning repeatable — data, features, training, deployment, monitoring — where the model is the small part.
Mobile App Architecture concept Mobile App Architecture Client architecture where the release cycle is not yours, old versions persist indefinitely, and the network is unreliable.
Modularity concept Architecture Fundamentals The degree to which a system is composed of parts that can be understood, changed and replaced independently.
Module Public Surface Module Exported Surface, Module Entry Points concept Modular Monolith The set of types a module lets other modules reach, which decides how much of it can be rewritten or extracted without touching anyone else's code.
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.
Multi-Region Architecture Regional Architecture Posture, Cross-Region Topology concept Multi-Region Architecture Running a system in more than one cloud region, which is a ladder of four distinct postures with different costs and guarantees rather than a single property - and the posture a team needs is rarely the one it…
Mutable Image Tag Repushed Tag, Tag Drift concept Artifact Management A registry tag that can be repointed to different content, so the same reference resolves to different artefacts over time or in different places - which makes deployments unreproducible and audit answers wrong.
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.
Network Performance concept Network Performance Latency is bounded by physics and bandwidth is bought — so architectural performance work is mostly about reducing round trips and moving data closer.
Nines Table concept Availability Mathematics The mapping between availability percentages and permitted downtime, and the cost curve that comes with it.
Noisy Neighbour Resource Contention, Co-Tenant Interference, Shared-Fate Degradation concept Platform Tenancy One workload degrading others by consuming a shared resource - and specifically the resources nobody set limits on, such as control-plane capacity, node network bandwidth and local disk.
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.
NoSQL Stores Non-Relational Databases concept NoSQL Stores Storage engines that trade query flexibility and cross-entity transactions for predictable performance at scale under known access patterns.
Object Storage concept Cloud Architecture Flat, HTTP-addressable storage for immutable blobs with rich metadata — effectively unlimited, cheap, and not a filesystem.