Hopefully, it’s approaching the finished product, but only sometimes. A good prototype will give testers a feel for how the product will work, the interactions that will take place with the application and, on some level, the look and feel. But in reality, if the web interface is very complex, you may only end up with a wireframe UI, or perhaps even a CLI, whilst you gain feedback on the product’s viability before embarking on a build-out of the user interface.