0:01Last time we saw that MCP is an agreement for getting outside information to the model.
0:05Now let's see how a real connection is organized, which program does what, starting with the app itself.
0:11Everything inside this boundary is one program on your machine, the chat window, the logic, the model inside it. MCP calls that whole program the host.
0:22It decides what gets connected, and what the model can see.
0:26Zoom in on the host. Now we need something inside it that speaks the protocol.
0:31For that, the host uses an MCP client, it manages a single connection.
0:35It opens the connection, sends the requests, and hands the results back to the host.
0:40One note on naming. Outside this series, people often call the whole app an MCP client. The specification keeps that name for this piece inside the host, and so will we.
0:51One last piece, the other end of the connection.
0:54This is an MCP server, a small, separate program offering one thing. Here it's a folder of documents.
1:00It can run on your machine or across the network. And it's usually a tiny program, not another assistant.
1:06And the model doesn't reach out directly, it goes through the MCP client. That's who opens the connection.
1:13So the client sends the request, the server responds, and the model gets its context, following the rules of the protocol.
1:21And the host isn't limited to one connection.
1:23Here's a server for web search, and another for the company database, each one its own small program.
1:30For every server it adds, the host creates another client.
1:34Three servers, three separate connections.
1:36That's the rule, every connection gets its own client, and they stay independent.
1:41So when your assistant fetches something now, you know every part involved.
1:45Each one has a single job, and together they carry context to the model, by agreement.
1:50Next time we'll look at what a server can actually offer. It turns out there are exactly three kinds of things.

Host, Client, and Server

Created by Abhyuday DesaiPublished 2 Oct, v1Runs 2 min 2 sec

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About this video

In Episode 03 of MCP Explained, we follow one request through a real MCP connection and name who does what along the way. The host is the whole program on your machine. Inside it, an MCP client manages a single connection. At the other end, an MCP server is a small, separate program offering one thing. Add more servers, and the host adds one client per connection.

You'll learn how to:

Identify the host: the whole app, which decides what gets connected and what the model can see
Understand the MCP client as the part inside the host that opens the connection, sends the requests, and hands the results back
See what an MCP server is, where it can run, and why it is usually a tiny program rather than another assistant
Follow the rule that every connection gets its own client, and why the connections stay independent
Learn how the word "client" is used outside this series, so the docs do not trip you up

This video is for developers hearing about MCP for the first time. No prior MCP knowledge is needed.

What changed

v102 Oct 2026abhydesai2 min 2 sec805b43c

First published version.

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