Glossary · Hosting and delivery
Client
A device or program—such as a browser—that requests information or actions from a server.
Also called: web client, HTTP client, API client, client-side
Definition
In client-server systems, the client initiates a request. A browser requesting a webpage is a client. A Python script requesting an API is also a client. The same machine can act as a client in one exchange and a server in another.
Why it matters
Knowing which side initiates a request helps clarify where credentials, validation, caching, and errors belong.
Common misunderstanding
“Client” can mean the customer in business language or the requesting program in technical language; context matters.
Related terms
Related system family: Hosting & Release
Sources
- How the web works (opens in a new tab) · MDN Web Docs
Last reviewed July 16, 2026