# COUNT ### Description `COUNT` returns the length of a list, dictionary, or string: * For a **list**, the number of elements. * For a **dictionary**, the number of key-value pairs. * For a **string**, the number of characters. `COUNT` and [`LEN`](/rule-language/operators/string-operators/len.md) are aliases and are fully interchangeable. By convention, `COUNT` is used with lists and dictionaries and `LEN` with strings, but either works for any of the three. ### Example ``` p is Person COUNT(p.nationalities) ``` This will result in the number of nationalities that are known for Person p in the case. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.atfinity.io/rule-language/operators/list-operators/count.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.