what the java command's jar option really does

Does the -jar option of the java command also compile the sources before running the main method? I believe so but i would like to have a better understanding of the internal process, from the man page you can clearly see a small workflow sequence:

-jar
             Execute a program encapsulated in a JAR file. The first argument is the name of a JAR file instead of a startup class name. In order for this option to work, the manifest of the JAR file must contain a  line  of
             the form Main-Class: classname. Here, classname identifies the class having the public static void main(String[] args) method that serves as your application's starting point. See the Jar tool reference page and
             the Jar trail of the Java Tutorial @

But it does not mention that it compiles the sources.