The Koa context object usually referred to as ctx is a combination of Node's request and response objects into a single object. A new context is created per request. It can be accessed in a middleware function as the first argument in the function.

It is often referenced in middleware as the ctx identifier, as seen in the following example:

app.use(async ctx => {
  ctx; // context object
  ctx.request; // Request object
  ctx.response; // Response object
});

The context object contains methods and properties which either belong specifically to the object or are aliases of methods and properties in the request and response objects.