Decoder. plain-English AI glossary

Template variables

● Core

Placeholders in a prompt template — like {{NAME}} or {user_email} — that are filled with actual data at runtime.

Think of it like

Mad Libs: "The {{ADJECTIVE}} {{NOUN}} ran {{ADVERB}}."

Example

Template: "Hello {{NAME}}, your order {{ORDER_ID}} ships {{DATE}}." Runtime fills in actual values.

How it actually works

Variables separate static structure from dynamic data. They prevent prompt injection if used correctly (validate input before substitution) and make templates reusable. Common implementations: string formatting, Jinja, custom systems.

For product teams

Clean, scalable prompting.

For engineers

Define variables clearly. Validate and sanitize input before substitution.

Prompt template — Part of prompt template design.

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