kliens

in English: client

basicwidespread

A client is the program or device that sends a request to another machine, the server, and displays or utilizes the received response.

In plain terms

Imagine sitting in a restaurant. You are the guest placing an order, and the kitchen prepares the meal. In the world of computing, the client is the guest: it requests something, while the server is the kitchen that fulfills the request. The term 'client' also means 'customer' in everyday language.

A client is your browser when you open a website, your email program when it downloads messages, and the chat app on your phone when it sends your query to a server running an AI model. Most of the work is often done not by your machine but by a remote server. The client's task is to forward the request and display the result.

In the AI world, the word has acquired a new layer of meaning. The program through which an agent connects to tools and data sources, such as an MCP server, is also a client. In this case, it is not a human but another piece of software sitting in the guest's seat.

How it works

The client initiates the connection: it speaks first, while the server waits for requests.
It sends the request according to a pre-recorded set of rules, or protocol, for example: 'I request this page' or 'answer this question'.
The server processes the request: it retrieves data, calculates, or runs an AI model. The client can wait for the response or do something else in the meantime.
The server sends back the response, which the client displays for you or forwards to another program.
The connection then closes or remains open for further messages. A single server can serve many clients simultaneously.

An everyday example

When you open the banking app on your phone and check your balance, the app is the client. It sends the request to the bank's server, which returns the amount, and your phone displays it. Your balance is on the bank's machines, not on your phone.

Who is affected

everyoneEvery browser, application, and chat program you use daily requests data from a remote server as a client.

developerIt must decide what runs on the client and what on the server, as this determines speed, security, and cost. → Code

entrepreneur, executiveWhen introducing an AI tool, you must know whether the company's data remains on the client or leaves the premises for an external server.

employeeIf the IT specialist asks you to update or reinstall the client, they are referring to the program running on your machine, not the remote system. → Work & HR

A common misconception

MythA client is always a human sitting in front of a computer, or the computer itself.

In realityClient role, not a person or device: the program that is currently making a request. The same machine or program can act as a client in one connection and as a server in another.

Limits and risks

A client is often worth little without a server: if there is no internet or the server goes down, most applications cannot work.
What the client sends leaves your machine, so before providing sensitive data, check where and to whom the request goes.
The client runs on your device and can therefore be modified or spoofed; for this reason, the server cannot blindly trust what it receives from the client.
An outdated client may pose a security vulnerability or simply fail to work with an updated server, so keeping it current is advisable.

Similar, but not the same

szerver – The server handles requests, the client sends them. These are the two sides of the same connection.
client (in a business sense) – In business, a client refers to the person or company hiring or buying; in computing, it refers to a program.
user – The user is the person operating the program, while the client is the program itself acting on their behalf.

Related concepts

Broader

kliens–szerver modell, szoftver, computer network

Narrower

browser, mobile application, MCP-kliens, API-kliens, thin client

On the edge

szerver, API, protokoll, frontend, MCP

A brief history

The word comes from the Latin 'cliens' (one under patronage, a protégé); in English it gave rise to the sense of 'customer'. In computing it became established as networks spread, and was already in use in the 1970s. The client–server architecture became common from the late 1980s, as personal computers were networked.

Where things stand

The client is one of the oldest and most general fundamental concepts in computer science; the web and mobile applications are all built on this division of roles. By the end of 2026, AI tools bring something new: agents also connect to tools and data sources as clients, increasingly via the MCP protocol.

Status: 2026 November

In the news

Appears in 34 Agent Age stories; the curve shows weekly occurrence in the news magazine.

Nvidia orders cloud clients to sell at least 51% of their services to non-Chinese firmsNov 3, 2026 · Agent Age
Publicis completes LiveRamp acquisition; clients can build their own AI systemsNov 2, 2026 · Marketing
Android Studio opens to any AI coding agent, ending Gemini exclusivityNov 2, 2026 · Code
New York State Bar: lawyers cannot bill for time saved by AINov 2, 2026 · Jog
AI models got 57% of financial advice wrong in Saturn testOct 26, 2026 · Money
WPP Media pilots ChatGPT Ads with Colgate, Ford, Henkel, RTL and VolksbankenOct 21, 2026 · Marketing
Mental health chatbots: RAND survey finds nearly one in five young people use themOct 19, 2026 · Health
McKinsey makes job applicants debate an AI client in interviewsOct 14, 2026 · Work & HR

Also known as

kliens · client · kliensprogram · client program · kliensoldal · client-side · client application · client app

Sources

This entry was machine-edited and has undergone machine expert review; the “In the news” section updates automatically from Agent Age stories.