A common way to connect
Suppose you ask an AI assistant where your order is. With MCP, the app can connect to software that offers an order lookup tool. That software is an MCP server; the part of the app that talks to it is an MCP client.
The server tells the app which tools, information, and reusable prompts it offers. If the model asks to use a tool, the app decides whether to run it and passes the result back to the model.
Connection is not permission
MCP defines how the app and server communicate. It does not make the server trustworthy or grant access to everything it offers. The app and connected software still need to check permissions, handle data safely, and ask for approval before important actions.