Understand the terms

A practical artificial intelligence glossary

Short, precise definitions to understand product claims, ask better questions and evaluate tools. 48 terms organized by use.

Study desk with a diagram notebook and cards representing artificial intelligence concepts.

48 terms

Foundations

Inference

Running an already trained model to produce output. It differs from training; its cost depends on the model and processed volume.

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Model card

A document describing a model, intended uses, limitations and information about training or evaluation. Check which version it covers.

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AI model

A system trained on data to produce an output from an input. One model can be offered through several applications.

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Large language model (LLM)

A model trained to process and generate language. It can write or summarize, but it is not a guaranteed database of facts.

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Token

A unit of text processed by a model: a word, part of a word or punctuation. Limits and costs are often expressed in tokens.

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Context window

The maximum amount of information a model can consider in one request, including input and output.

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Interacting with a model

Structured output

A response following a defined format, such as a JSON schema. Valid formatting does not prove the values are correct.

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Prompt injection

An attempt to make a model follow instructions inserted into input or documents instead of the authorized task. Treat external documents as untrusted data.

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Prompt

Instructions and context given to an AI system. A useful prompt states the intended result, constraints and format.

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System instruction

An instruction shaping an assistant’s behavior. It does not replace technical access and data controls.

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Multimodal

The ability to process or produce several content types, such as text, images, audio and video.

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Temperature

A parameter affecting output diversity in some models. A lower value does not guarantee accuracy.

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Answers and sources

Optical character recognition (OCR)

Converting characters in an image into text. Recognition does not validate reading order, table structure or value accuracy.

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Reranking

Reordering retrieved documents by relevance to a query. It does not replace checking the content of the documents.

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Provenance

The origin and history of information: document, author, date and transformations. Provenance helps trace the support for a claim.

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Source freshness

How well a source’s date fits the question. Distinguish publication date, event date and the corpus’s last synchronization.

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Hallucination

A plausible but false, invented or unsupported answer. A source or citation can also be fabricated.

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Grounding

A method linking an answer to identifiable documents. It helps verification, but a source can still be misread.

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Retrieval-augmented generation (RAG)

An architecture retrieving passages from a corpus before passing them to a model for its answer. Quality also depends on the documents and retrieval.

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Source citation

A reference shown with an answer so a claim can be traced. Open the source and check the passage, date and context.

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Architecture

Embedding

A numerical representation used to compare semantic similarity. Nearby items are not necessarily equivalent or true.

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Vector database

A system storing vectors and retrieving nearby items. In RAG it helps select passages but does not verify their accuracy.

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Fine-tuning

Additional training on targeted examples to change model behavior. It does not replace an up-to-date document collection.

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Application programming interface (API)

A technical interface through which an application requests an AI service. Costs, quotas and data rules depend on the plan.

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Agents and automation

Idempotency

A property where repeating an operation has no additional effect compared with executing it once. Useful for preventing duplicates during retries.

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Least privilege

Granting only permissions needed for a task and for the required duration. An agent should not receive all access by default.

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Retry

Re-execution after failure. Limit attempts, distinguish temporary from permanent errors and prevent duplicate writes.

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AI agent

A system combining a model, goals, tools and decision steps to complete a task. Its autonomy should be bounded by permissions.

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Tool calling

A mechanism through which a model asks an application to run a function such as search or calculation. The application controls execution.

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Workflow

A sequence of steps connecting people, data and tools. Reliable automation plans for errors, recovery and approval.

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Human review

A decision or check performed by a person before or after a system action, useful when errors could have significant consequences.

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Evaluation

Critical error

An error whose consequence makes an output unacceptable even if other criteria are satisfied. Define it before the trial, such as a wrong recipient, incorrect amount or ignored permission.

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Abstention

Declining to answer or act when information or authorisation is insufficient. Evaluate it on explicitly out-of-scope cases.

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Acceptance criteria

Observable conditions set before a trial to determine whether a result is usable. Include errors that require rejection.

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Cost per accepted result

Total trial cost divided by results passing checks, including service, calls, preparation and correction. It differs from generation price.

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Observability

Understanding system behaviour through logs, metrics and traces. Retain useful evidence without unnecessarily logging sensitive data.

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Evaluation set

A stable set of representative cases and criteria used to compare versions of an AI system on a defined task.

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Benchmark

A standardized evaluation comparing systems under a stated method. A strong public score does not guarantee quality on your data.

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Regression

A decline in behavior that previously worked, sometimes after a change to a model, prompt or data.

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Latency

The time between a request and a usable result. Also measure retrieval, tool execution and human review time.

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Data and rights

Data portability

The technical ability to export and reuse data in another system. Check formats, attachments, metadata and reimport; downloading alone does not prove portability.

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Reversibility

The ability to leave a tool or return to an earlier state with controlled effort. Verify it with a restoration trial rather than an export promise alone.

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Self-hosting

Operating software on infrastructure you manage. It requires maintenance and backups and does not guarantee all calls remain local.

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Data residency

Locations where data is stored or processed. The publisher’s country is insufficient: check regions, subprocessors and contractual documents.

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Personal data

Information that identifies a person directly or indirectly. Check necessity and processing terms before sharing it.

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Data retention

The period for which a service stores inputs, outputs or logs. It varies by product, plan and settings.

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Open weights

A model whose trained parameters are distributed under a license. It does not always mean the data or code is open.

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Usage license

Terms governing use, redistribution or modification of a model, tool or content. Check the exact license before commercial use.

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Further references

Apply these concepts to a comparison trial →