Prompt engineering glossary

Short definitions + a copy-paste example per term. Pick one and open it.

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This glossary covers concepts that commonly break prompts: ambiguity, missing delimiters, inconsistent output, or hallucinations. Each term includes a short definition and a copy-ready example.

If you need strict outputs, start with strict JSON. If you want to tailor prompts to each AI, check prompts by model.

System prompt
The instruction layer a model treats as highest priority: its role, rules and boundaries for the whole conversation.
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Few-shot prompting
Including one to five worked examples in the prompt so the model copies their format, tone and level of detail.
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Delimiters
Markers such as triple quotes, headings or XML-style tags that separate your instructions from the text the model must work on.
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Constraints
Explicit, testable limits on the answer — length, tone, scope, allowed sources, forbidden claims, tech stack — that keep it useful.
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Temperature
A sampling setting that controls how random a model's word choices are: lower values are steadier, higher values more varied.
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Hallucinations
Fluent, confident output that is false or unsupported — invented facts, figures, quotes or sources — presented as if it were true.
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Prompt injection
An attack in which instructions hidden in content the model reads — a web page, an email, a document — try to override your own.
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JSON schema
A formal description of the shape of a JSON document — keys, types, required fields, allowed values — used to constrain and validate model output.
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Role prompting
Assigning the model a role — editor, tutor, auditor — together with the criteria that role should apply, to set tone and expectations.
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Evaluation
Testing a prompt on a fixed set of inputs and scoring the outputs against acceptance criteria, so improvements can be measured instead of guessed.
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Zero-shot prompting
Asking a model to do a task from the instruction alone, with no examples, relying on what it already learned in training.
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Context window
The maximum amount of text, counted in tokens, that a model can take in and produce in a single request.
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Chain-of-thought prompting
Asking a model to work through intermediate reasoning steps before giving its final answer, which helps on multi-step problems.
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Prompt chaining
Splitting a complex task into a sequence of smaller prompts, where each step's output becomes the next step's input.
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Structured output
Getting a model to answer in a fixed, machine-readable format — JSON, a table, labelled fields — instead of free-form prose.
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Tokens
The chunks of text — whole words, word pieces or punctuation — that a model reads and writes; context limits and pricing are counted in them.
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Top-p (nucleus sampling)
A sampling setting that limits the model's next-word choice to the smallest set of tokens whose probabilities add up to p.
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Retrieval-augmented generation (RAG)
A pattern where relevant passages are retrieved from a knowledge source and put into the prompt so the model answers from them.
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Negative prompting
Telling the model what to avoid — a tone, a claim, a format, a topic — alongside what to do, so unwanted output is ruled out explicitly.
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Context engineering
Deciding what information goes into the model's context — instructions, documents, examples, history, tool results — and in what order and form.
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