An MCP server (Model Context Protocol server) is a small program that gives an AI model — like Claude or GPT — access to external tools, data, or services in a standardized way. Think of it as a plug-in adapter: the AI speaks one universal language (MCP), and the server translates that into calls to a specific tool, like a database, a calendar, or a code executor.

MCP was introduced by Anthropic in 2024 as an open standard for connecting AI assistants to the outside world. Before MCP, every developer had to build custom integrations for each AI and each tool — messy and hard to scale. MCP gives everyone a shared protocol, so a tool built once can work with any AI that supports the standard.

In practice, when an AI needs to, say, search the web or read a file, it sends a request to the MCP server, which does the actual work and returns the result. This keeps the AI model separate from the tools it uses, making systems easier to build, swap out, and secure.