Wow, in just a few steps, we created a brand new application! Granted, it does not do much, to say the least. Yet, those simple actions are fundamental to the comprehension of more advanced concepts seen in further chapters. So, let's catch our breath and see what really happened under the hood.
http://localhost:8080/myfirstvaadinapp/vaadin can be decomposed in the following three parts, each part being handled by a more specific part:
http://localhost:8080is the concatenation of the protocol, the domain, and the port. This URL is handled by the Tomcat server we installed and started previously, whether inside the IDE or normally.
/myfirstvaadinappis the context root and references ...