# Content Negotiation Content negotiation selects an appropriate representation of a resource for a client or channel. HTTP commonly negotiates through headers; application-level systems can also select representations through routes, parameters, or declared adapters. XDO's `_do_as` layer applies the broader representation-selection idea to HTML, CSV, XML, RSS, tables, and other outputs. AutoSites feed parameters similarly shape one content record for different downstream channels. Related: [[wiki/Output Projection|Output Projection]], [[wiki/Data Serialization|Data Serialization]], [[wiki/Content Syndication|Content Syndication]]. Source: [MDN — HTTP content negotiation](https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/Content_negotiation)