Glossary · Privacy and data governance
User agent
Information a client sends with a web request describing its software and sometimes device or platform characteristics.
Also called: browser user agent, user-agent string
Definition
The HTTP User-Agent header traditionally identifies the requesting software and may include browser, rendering engine, operating-system, or device tokens. Its content can be reduced, altered, or imitated and should not be treated as reliable identity proof.
Why it matters
User-agent data can support compatibility and abuse diagnosis, while also adding privacy and data-retention considerations when stored in logs.
Common misunderstanding
A user-agent string is not a verified person or device identity and should not be trusted as a sole security control.
Related terms
Related system family: Secure Integrations & Custom Tools
Sources
- User-Agent request header (opens in a new tab) · MDN Web Docs
- HTTP (opens in a new tab) · MDN Web Docs
Last reviewed July 16, 2026