What is Delimiters?
Also called: XML tags in prompts · triple quotes
Delimiters are markers — XML-style tags, triple quotes, headings — that separate the parts of a prompt so the model knows which text is instruction, which is data, and which is an example.
When you paste a document into a prompt, the model has to decide where your instructions end and the document begins. Delimiters make that unambiguous: wrap the document in <document>…</document> or """…""", label examples, and put the task after a clear heading.
Claude models were trained on a lot of XML-tagged text and respond especially well to tags; the technique helps on every model. It also reduces prompt-injection risk, because text inside a data block is easier to treat as data.
<instructions>Summarise the email in 3 bullets.</instructions> <email> …pasted text… </email>
- Use the same delimiter style throughout a prompt.
- Put the instruction before and (for long inputs) after the data.
- Refer to blocks by name: "using only the <email> above".
Use it right now
Ask our brain anything on the homepage — it remembers the whole conversation — or write a brief in the Studio and see the prompt it compiles to.