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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

2205 terms shown.

Term Kind Topic What it is
Least-Privilege Tooling Bounded Tool Permissions practice Prompt Injection Defence Giving each tool the narrowest possible capability and enforcing authorisation at the tool - the decisive control when a model's instructions can be influenced by untrusted content.
Legacy Assessment practice Legacy Assessment Establishing what a legacy system actually does, what depends on it, and what it costs, before deciding what to do with it.
Legacy Headroom Budget Legacy Capacity Allocation, Integration Throughput Quota practice Legacy Integration Patterns The measured spare throughput of a legacy system after retry amplification, batch overlap and organic growth are deducted, allocated to new consumers as enforced quotas rather than published as available capacity.
Legacy Integration practice Legacy Integration Connecting modern services to systems that cannot be changed — where the constraints are as much commercial and operational as technical.
Legacy Side-Effect Inventory Trigger Inventory, Write Consequence Map practice Strangler Fig The enumerated list of triggers, stored procedures, scheduled jobs and integrations that fire as a consequence of a legacy write, which determines whether a capability can be moved incrementally at all.
Legacy System Assessment practice Legacy Assessment A structured evaluation of a system's business value, technical condition and risk, used to decide what to do with it rather than to describe it.
Legacy Wrapping pattern Legacy Integration Patterns Placing a modern interface in front of a legacy system so that consumers integrate with the wrapper rather than with the legacy system directly.
Legal Hold practice Records Retention & Legal Hold Suspending deletion for specific records because of anticipated litigation or investigation, which must override the retention schedule and be provable.
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.
Lift and Shift pattern Rehosting Moving an application to new infrastructure with minimal change, trading optimisation for speed and low migration risk.
Lineage Coverage Harvest Coverage, Lineage Completeness Ratio metric Data Catalog The share of known data assets whose upstream and downstream edges were successfully derived on the latest harvest, which is the only signal that separates an asset with no dependencies from one the parser cou…
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.
LinkedIn and the Origin of Kafka case-study API & Integration Kafka was built to replace point-to-point data integration between many systems with a single durable log that any system could publish to and any number could read.
LinkedIn Databus: Change Capture as a Product Databus case-study Change Data Capture LinkedIn built a change capture system so that derived stores — search, graph, caches — could stay current without every application dual-writing to them.
LinkedIn Project Inversion: Stopping to Fix the Road Inversion case-study Technical Debt LinkedIn halted feature development for roughly two months to rebuild its deployment and development infrastructure, because the tooling had become the constraint on everything.
LinkedIn: Kafka and the Unified Log The Log, Kafka Origin case-study Event Streaming LinkedIn replaced a tangle of point-to-point data pipelines with a single durable log, turning an O(n²) integration problem into an O(n) one.
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.
Little's Law Applied to Pools practice Connection Pooling Using L = λW to size connection and thread pools from measured throughput and latency rather than from a default.
Little's Law in Practice metric Little's Law L = λW — concurrency equals arrival rate times latency — and the reason a slowdown becomes an outage.
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.
LLM Evaluation Evals practice AI-Era Architecture A repeatable measurement of whether an AI system's outputs are good enough, on cases that reflect the actual task.
LLM-as-Judge practice LLM Evaluation Using a language model to score another model's outputs against criteria, making evaluation scalable at the cost of introducing the judge's own biases.
Load Balancer Pre-Warming LCU Reservation, Balancer Warm-Up practice Load Balancing Reserving or requesting minimum load-balancer capacity before a scheduled step change in traffic - because a managed balancer is itself an autoscaled fleet whose provisioning loop is slower than a product laun…
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.
Load Shedding pattern Load Shedding Deliberately rejecting a portion of incoming work so the system continues serving the remainder at acceptable latency, rather than degrading for everyone.
Load Testing practice Performance & Capacity Driving a system with realistic traffic at a target volume to verify it meets its performance targets before real users do.
Load Testing in Practice practice Load Testing Verifying behaviour under expected load — where realism of workload and data matters more than the number of virtual users.
Load-Coupled Fault Injection Fault Injection Under Load, Contention Testing practice Chaos Engineering Injecting dependency faults while the system is at realistic peak load, because timeouts, pool sizes and breaker thresholds only reveal whether they are correct under contention.
Local First Write pattern Offline-First Committing to local storage first and treating the server as an eventual replica, which makes the interface responsive and connectivity an optimisation.
Local Revert On-Device Rollback, A/B Partition Update, Watchdog Revert pattern OTA Updates A device automatically returning to its previous known-good software or configuration when the new one fails, without needing to contact a server - the only mechanism that works when the failure prevents commu…
Locale Aware Formatting practice Internationalisation Rendering dates, numbers, currencies and names according to the user's locale rather than the developer's, using the platform rather than hand-written logic.
Locale Fallback Chain Language Negotiation Chain, Locale Resolution Order pattern Internationalisation The declared order in which a system degrades from a requested locale to one it can actually serve - and the decision about which values are allowed to degrade at all.
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 Level Discipline practice Logging Consistent semantics for log severity so that levels can be used for routing, alerting and cost control.
Log Management practice Log Management The pipeline, storage, retention and access model for logs — where cost and compliance meet operational need.
Log Retention Tiering practice Log Management Storing log data at different resolutions, costs and access latencies according to how old it is and how likely it is to be queried.
Log Sampling Budget Log Volume Budget, Log Ingest Quota practice Logging An owned per-service allowance of log volume, spent by deciding which record classes are kept whole and which are sampled by trace - the control that turns an invisible shared cost into a decision a team makes…
Log Schema Consistency practice Structured Logging Enforcing the same field names, types and semantics for structured log records across every service, so cross-service queries are possible.
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.
Log-Based CDC pattern Change Data Capture Capturing changes by reading the database's own write-ahead log, which sees every change with no load on the source and no application involvement.
Log-Based Ingestion pattern CDC Pipeline Design Building the pipeline around a database's own change log — an initial snapshot followed by a continuous delta stream, with the two stitched together.
Logging practice Logging Emitting events a human or a query can reason about later — where the discipline is structure, sampling and what you refuse to log.
Logical Date Partitioning Execution Date, Idempotent Reprocessing practice Batch Orchestration Making every batch task a pure function of a logical date, so that any run can be repeated safely and a backfill is a range of independent executions.
Logical Shard Virtual Shard, Shard Slot pattern Sharding Patterns A unit of partitioned data that routing targets by name rather than by machine, so data can be moved between physical hosts without changing how anything is addressed.
Long Task Main-Thread Blocking Task, Long Animation Frame metric Web Performance Budgets Any single piece of work holding the browser's main thread for more than 50 ms, during which no input is handled and nothing is painted - the unit in which an unresponsive page is actually measured.
Long-Running Operation SLO Operation Completion Objective, Terminal-State Objective pattern Platform SLOs A reliability objective shaped for multi-minute platform operations like deploys and provisioning - share of runs reaching a terminal state within a deadline with no manual repair - replacing availability perc…
Machine-Checkable Standard Executable Standard, Automated Conformance Rule practice Architecture Governance An architecture rule written so that a program can decide whether a change complies, enforced at merge or deploy time, which is the only form of governance whose capacity scales with the rate of change.
Maersk and NotPetya: Recovery from a Single Surviving Copy NotPetya 2017 case-study Backup Strategies A destructive malware outbreak encrypted Maersk's estate globally, and the domain controllers were recovered only because one office had been offline during the attack.
Mainframe Modernisation practice Mainframe Modernization Replacing or reducing dependence on a core system that is reliable, undocumented, and central to the business.
Mainframe Offload pattern Mainframe Modernization Moving read traffic and selected processing off a mainframe onto modern platforms, reducing cost and unblocking new development without replacing the core.
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 Substitution pattern Replatforming Replacing a self-managed component with a managed equivalent during migration, without changing the application's architecture.
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.
Managed versus Self-Managed practice Managed vs Self-Managed Whether to run a component yourself — a decision that should default to managed and require a specific articulated reason to deviate.