# HTTP headers: what it is and how it works · Zorraquino
> HTTP headers are the fields of information that accompany every request and response between a browser or other client and a web server.
URL: https://www.zorraquino.com/en/dictionary/internet/http-header.html

# HTTP headers

HTTP headers are the fields of information that accompany every request and response between a browser or other client and a web server

What it means, how it is used and where it comes up, with its related concepts.

[The whole glossary](https://www.zorraquino.com/en/dictionary)

## What it is and how it works

Each header is a name–value pair describing part of the exchange: the content type (Content-Type), accepted language, cookies, caching instructions (Cache-Control), redirects (Location) or the user agent making the request.

They matter for performance, security and SEO. Headers such as Strict-Transport-Security and Content-Security-Policy protect against attacks; X-Robots-Tag tells search engines not to index a file; and the response status code, sent alongside the headers, shows whether a page exists, has moved or has failed. HTTP/2 and HTTP/3 compress headers, but their role is the same.

Also known as

HTTP header fields

Topics

[Technology and data](https://www.zorraquino.com/en/dictionary/category/tecnologia-y-datos)

## Related concepts

- [HTTP](https://www.zorraquino.com/en/dictionary/internet/http.html)
- [HTTP/2](https://www.zorraquino.com/en/dictionary/internet/http2.html)
- [Cache](https://www.zorraquino.com/en/dictionary/internet/cache.html)