Components

• Logically, components are containers for modules - or other components - which express their interfaces and dependencies via WIT.
• Conceptually, components are self-describing units of code that interact only through interfaces instead of shared memory.
• Physically, a component is a specially-formatted WebAssembly file. Internally, the component could include multiple traditional ("core") WebAssembly modules, and sub-components, composed via their imports and exports.

The external interface of a component - its imports and exports - corresponds to a world. The component, however, internally defines how that world is implemented.

For a more formal definition of what a component is, take a look at the Component Model specification.