Prompt template
Also called prompt variables, reusable prompt, parameterised prompt
A reusable prompt with blanks, like {{AUDIENCE}}, that you fill in each time you use it.
A prompt template is a prompt written once and reused many times, with placeholders for the parts that change. On this site, placeholders are written in capitals inside double curly braces, such as {{EMAIL_TEXT}} or {{AUDIENCE}}. Other tools use single braces, square brackets or dollar signs, but the idea is the same.
Templates separate the stable part of a prompt, which you test and improve, from the variable part, which is different every time. That makes results more consistent and lets you share good prompts with a team. In software, templates are filled in by code before the prompt is sent to a model API, often from a database or a form.
A good template names its variables clearly, explains any that are not obvious, and keeps instructions outside the variables. It also handles the case where a variable is empty or unexpected, for example by telling the model what to do if the text is missing.
Example
A support team uses: "Reply to this customer message from {{CUSTOMER_NAME}}: {{MESSAGE}}. Our refund policy: {{POLICY}}. Answer in the first sentence, under 100 words." Agents fill in three fields instead of writing a prompt from scratch for each ticket.
Common mistake
Leaving placeholders unfilled. Sending "{{AUDIENCE}}" to a model literally confuses it, and it may invent an audience or treat the braces as content. Before sending, scan for any remaining braces, or use a tool like this site's fill-in fields that replaces them for you.