---
title: Apps
description: Web Apps and MCP Servers, through which people and agents use the Ontology.
---

An **App** is a Resource through which people or agents use the Ontology. A web App serves people in a browser, and an **MCP Server** exposes the Ontology to agents.

## App Routes

An **App Route** is an App's hostname on a Branch. The same App can serve one Route for `main` and another for a Branch under review, each reading that Branch's data.

## Who an App acts for

An App's requests act for a principal: a signed-in user, a service user, or an anonymous principal, such as a visitor to a public App. The principal's Markings decide which data each request reaches.