Tapestry components are "black boxes" that are involved with both rendering HTML responses and responding to HTTP requests.

A Tapestry component is defined by its specification. The specification is an XML file that defines the type of the component, it parameters, the template used by the component, any components embedded within it and how they are 'wired up', and (less often) any assets used by the component.

At runtime, the specification is used to identify and instantiate a class for the component. When the page containing the component is rendered, the component will access its HTML template to find the static HTML and embedded components it will render.