> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mcp-b.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Essential concepts

> Background concepts for understanding WebMCP, MCP-B, and their design boundaries.

The explanations below cover the basic background concepts behind WebMCP and MCP-B, focusing on design boundaries, tradeoffs, and terminology.
A fuller editorial series will live on [SigVelo](https://sigvelo.com/blog/) soon.

<CardGroup cols={2}>
  <Card title="What is WebMCP?" href="/explanation/what-is-webmcp" />

  <Card title="WebMCP vs MCP" href="/explanation/webmcp-vs-mcp" />

  <Card title="Core vs MCP-B extensions" href="/explanation/strict-core-vs-mcp-b-extensions" />

  <Card title="Runtime layering" href="/explanation/architecture/runtime-layering" />

  <Card title="Transports and bridges" href="/explanation/architecture/transports-and-bridges" />

  <Card title="Tool lifecycle" href="/explanation/architecture/tool-lifecycle-and-context-replacement" />

  <Card title="Security" href="/explanation/design/security-and-human-in-the-loop" />

  <Card title="Spec status" href="/explanation/design/spec-status-and-limitations" />
</CardGroup>

For executable guidance, use [Tutorials](/tutorials/index) and
[How-to guides](/how-to/index). For API details, use [Packages](/packages/index)
and the WebMCP standard references.