# Gadgets In this section we want to walk you through some gadgets. Gadgets are sub-circuits that were built by others that you can make use of. For example, if somebody else spent months implementing the hash function keccak and ensuring it was both safe and optimised, why would you then build it all yourself again from scratch? You wouldn't of course, you would make use of their gadget for it (provided you trusted its quality). Other gadgets include a range gadget or ECDSA signature verification in arbitrary fields. --- # 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://erroldrummond.gitbook.io/halo2-tutorial/section-3/gadgets.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.