Terminology

2185 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 areas2185 Architecture Fundamentals77 Distributed Systems107 Data Architecture110 Cloud Architecture89 Networking88 API & Integration Architecture82 Reliability & Resilience75 Observability70 Performance & Capacity Engineering72 Security Architecture81 Cost Architecture & FinOps66 Business Architecture67 Architecture Communication67 Enterprise Architecture66 Legacy Modernization66 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 concept785 practice729 pattern362 metric125 case-study77 tool62 protocol45

66 terms shown.

Term	Kind	Topic	What it is
Amortised Cost View Effective Rate Reporting, Commitment-Adjusted Showback	practice	Cost Allocation	Reporting each team's spend at the effective discounted rate spread across a commitment term, so a team's number moves only when its own usage moves rather than when the finance department buys something.
Architecture Cost Model	practice	Cost & FinOps	A calculation, made during design, of what an architecture will cost to run at expected and at peak volume.
Billable-Event Metering Contract-Aligned Metering, Obligation-Point Metering	practice	Licence & Vendor Costs	Recording the event a contract actually charges for at the point in the system where that obligation is created, rather than inferring it from delivery telemetry that caching and retries make unreliable.
Bin-Packing Efficiency Packing Density, Requested-to-Allocatable Ratio	metric	Rightsizing	The share of purchased node capacity that scheduled workloads have actually reserved, which is the missing link between a rightsizing campaign and the invoice it was supposed to reduce.
Budget Guardrail	practice	Cost Governance	An automated control that constrains or alerts on spend before an invoice arrives, rather than reporting overspend after the fact.
Capacity Insurance Reliability Headroom, Standby Capacity	concept	Waste Elimination	Capacity that produces no value in normal operation and exists to make failures survivable - which looks identical to waste on a utilisation dashboard and must be defended explicitly.
Chargeback and Showback	practice	Cost & FinOps	Attributing cloud cost to the teams that generate it — either informationally (showback) or by moving it onto their budget (chargeback).
Chunk-Level Deduplication Content-Defined Chunking, Sub-File Deduplication	pattern	Storage Costs	Splitting files into content-addressed pieces at boundaries chosen by the data itself, so repeated rewrites of a large artifact store only the bytes that changed rather than a new full copy.
Cloud Egress Cost	concept	Network & Egress Costs	The asymmetric pricing where data entering a cloud is free and data leaving is charged, which shapes architecture more than most teams expect.
Cloud Pricing	concept	Cloud Pricing Models	How cloud providers charge, which dimensions dominate, and the pricing structures that reward architectural rather than operational responses.
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.
Commitment Coverage	metric	Reserved & Committed Capacity	The proportion of steady-state usage covered by discounted commitments, balanced against the risk of committing to capacity that is no longer needed.
Commitment Floor Minimum Spend Obligation, Contracted Spend Floor	concept	Reserved & Committed Capacity	The minimum spend a contract obliges you to pay regardless of usage, which makes efficiency gains unrealisable until the term ends and therefore sets the pace of cost programmes and migrations.
Compute Optimisation	practice	Compute Optimisation	Reducing compute spend through sizing, scheduling, purchasing model and architecture — in increasing order of both effort and payoff.
Cost Accountability Model	practice	Showback & Chargeback	The arrangement determining whether teams merely see their costs or are financially charged for them, and the behaviour each produces.
Cost Allocation	practice	Cost Allocation	Attributing spend to the team, service or customer that causes it — the prerequisite for every other cost conversation.
Cost Allocation Tagging	practice	Cost Allocation	A mandatory, enforced tagging scheme that attributes every resource to an owner, so spend can be understood and acted on below the level of the whole account.
Cost Attribution Tagging Strategy, Cost Ownership	practice	Cost Allocation	Assigning every unit of infrastructure spend to a team and a product, enforced at resource creation - the prerequisite without which no other cost control works.
Cost Driver Scaling Driver, Cost Dimension	concept	Architecture Cost Modelling	The measurable quantity whose growth causes a cost to grow - identifying it correctly is what makes a cost model predictive rather than descriptive.
Cost Governance	practice	Cost Governance	The guardrails, budgets and approval structures that prevent cost surprises without becoming a bottleneck.
Cost Model Sensitivity	practice	Architecture Cost Modelling	Identifying which assumptions in a cost projection dominate the outcome, so effort goes into the estimates that actually matter.
Cost of Downtime	metric	Cost vs Reliability	The quantified business impact of unavailability per unit of time, which converts reliability investment from an argument into an arithmetic comparison.
Cost per Request	metric	Cost per Request	Total cost divided by units of business value — the metric that makes cost comparable across time, scale and design options.
Cost per Request	metric	Cost & FinOps	The fully-loaded infrastructure cost of serving one request, and the unit that makes architectural cost decisions comparable.
Cost Telemetry Lag Billing Data Delay, Spend Reporting Latency	concept	Cost Governance	The delay between spend being incurred and appearing in billing data, which sets a floor on how fast any detective cost control can possibly react and explains why budget alerts arrive after the money is gone.
Cost versus Reliability	concept	Cost vs Reliability	Reliability is bought with redundancy and headroom, both of which cost money — so the target must be chosen rather than assumed.
Cost vs Reliability Trade-off	concept	Cost & FinOps	The non-linear relationship between availability and spend, which makes each additional nine roughly an order of magnitude more expensive.
Data Gravity Data Inertia, Locality Pull, Egress Pull	concept	Network & Egress Costs	The tendency of large data to attract compute and services toward it, because moving data across billed or slow boundaries is expensive while moving computation to the data is cheap.
Dropbox's Move Off S3 Magic Pocket	case-study	Cost & FinOps	Dropbox moved the majority of its file storage off Amazon S3 onto custom infrastructure, reporting savings that its S-1 filing put at roughly $75 million over two years.
Dual-Run Cost Overlap Migration Cost Hump, Parallel-Running Overlap	concept	Architecture Cost Modelling	The period in any platform migration when both the old and the new system are paid for at once, which raises the run rate before it falls and sets the true date on which a cost business case begins to pay back.
Egress Cost Data Transfer Out	concept	Cost & FinOps	The charge for moving data out of a cloud provider or across its zones and regions — usually the least-anticipated line on a cloud bill.
Egress Path Analysis	practice	Network & Egress Costs	Tracing where data physically moves in an architecture, because transfer charges follow paths that appear nowhere on the diagram.
Egress Pricing	concept	Cloud Pricing Models	The asymmetric charging model in which data entering a cloud is free and data leaving is billed, shaping architecture more than compute pricing does.
Elastic Cost Blindness Soft Constraint Failure, Invoice-Delayed Feedback	concept	Cost Governance	The failure mode of elastic platforms - the system satisfies any request rather than refusing it, so a capacity problem becomes a cost problem that reports itself a month late.
FinOps	practice	Cost & FinOps	The practice of giving engineering teams visibility into and accountability for the cost of what they build and run.
FinOps Operating Phases	practice	FinOps Practice	The inform, optimise and operate cycle through which an organisation builds cost management into normal engineering practice.
FinOps Practice	practice	FinOps Practice	The operating model that makes cost a continuous engineering concern rather than a periodic finance exercise.
Fully-Loaded Tenant Cost True Cost to Serve, Cost Per Tenant, Loaded Unit Cost	concept	Unit Economics	The total cost of serving one tenant including the per-tenant floors that do not scale with usage - infrastructure minimums, control-plane overhead, fleet operations, support and abuse - which is what makes sm…
Funnel-Stage Cost Ratio Attempts per Conversion Cost, Pre-Conversion Cost Multiple	metric	Unit Economics	The cost incurred by all the attempts that precede one revenue event, expressed per revenue event, which exposes the case where making each attempt cheaper makes the business more expensive.
Hidden Cost Categories	concept	Total Cost of Ownership	The recurring costs routinely omitted from total-cost-of-ownership comparisons, which usually exceed the licence or infrastructure line everyone argues about.
Idle Cost	concept	Cost per Request	The portion of infrastructure spend incurred regardless of traffic, which determines how cost per request behaves as volume changes.
Instance Family Selection	practice	Compute Optimisation	Matching a workload's resource profile to a machine type designed for it, which is frequently a larger saving than reducing size.
Interruption Tolerance	concept	Spot & Interruptible Capacity	The property that determines whether a workload can use heavily discounted pre-emptible capacity, defined by what happens when an instance is reclaimed at short notice.
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.
Observability Cost	concept	Observability Cost	Monitoring spend that grows with traffic and frequently reaches a meaningful fraction of infrastructure cost — controlled by sampling, cardinality and retention.
Orphaned Resource	concept	Waste Elimination	Infrastructure that is billed but serves nothing, typically left behind when the thing it supported was deleted.
Pass-Through Cost of Goods Sold Third-Party Unit Cost, Supplier Pass-Through Term	concept	Cost per Request	The part of the cost of serving one unit that is paid to a third party per transaction, which infrastructure optimisation cannot reduce and which eventually decides whether unit cost keeps falling.
Reserved and Committed Capacity Savings Plan, Committed Use Discount	practice	Reserved & Committed Capacity	Trading a commitment to spend for a substantial discount, where the risk is committing to an architecture you are about to change.
Retrieval-Cost Trap Archival Access Cost, Cold Tier Scan Penalty	concept	Storage Costs	The failure where moving data to an archival tier saves storage cost and a scanning access pattern then spends more on retrieval than the tiering saved.
Rightsizing	practice	Rightsizing	Matching provisioned resources to measured need — the fastest large cost reduction available, and one that must respect headroom requirements.
Shared-Service Commons Free-at-Point-of-Use Platform, Uncharged Internal Platform	concept	Showback & Chargeback	The failure mode where cost allocation prices each team's own resources but leaves internal platforms free to use, so teams move cost onto the shared estate instead of removing it and total spend rises while e…
Showback and Chargeback	practice	Showback & Chargeback	Showing teams their costs, or actually billing them — two different mechanisms with different incentive effects and different failure modes.
Spot Capacity Preemptible, Interruptible Instances	practice	Spot & Interruptible Capacity	Using a provider's spare capacity at a steep discount, in exchange for the provider being able to reclaim it at short notice.
Storage Costs	concept	Storage Costs	Storage is cheap per gigabyte and expensive in aggregate — controlled by retention and tiering rather than by unit price.
Storage Lifecycle Policy	practice	Storage Costs	Automated rules that move objects between storage classes as they age, matching cost to the declining probability that data will be read.
Structural Cost Attribution Boundary-Based Allocation, Attribution Without Tagging	practice	Cost Allocation	Deriving cost ownership from deployment boundaries - account per workload, cluster per team - rather than from tags, because tagging discipline never survives contact with a growing organisation.
Telemetry Spend Ratio	metric	Observability Cost	Observability cost as a proportion of the infrastructure it observes, used as a tripwire for a category that grows silently.
Total Cost of Ownership TCO	concept	Total Cost of Ownership	The full lifetime cost of a choice — infrastructure, licences, and the engineering time that is usually the largest term and the one omitted.
Total Cost of Ownership TCO	metric	Cost & FinOps	The full lifetime cost of a capability, including the people, operations, upgrades and exit that a licence comparison leaves out.