In production, people need to configure the servlet so that they can offer the users a user-friendly url. This can be done using some XML files. You are just touching the tip of iceberg.
For instance, as I hit
I really don't have an idea what kind of servlet that hello is.
Java classes have full name, including package structure. As we say String, we mean java.lang.String. Sometimes, we can simply say String, Hashtable, HashSet, URLConnection, .... because we have imported the library package. As we refer to a Java class from outside of Java, we have to use the full name. Full Name!
Here are some useful websites:
You can find more.