The main method accepts a single argument: an array of elements of type String.
public static void main(String args)
This array is the mechanism through which the runtime system passes information to your application. For example:
java MyApp arg1 arg2
Each string in the array is called a command-line argument.
Windows uses the PATH environment variable to find programs to execute. The PATH consists of a list of directories where Windows will look for *.exe files (executable programs). Normally, you'll want to add the bin directory of your JDK installation directory to the PATH, so that Windows can find the JDK tools when you're working in a command prompt window. See Updating the PATH Environment Variable in the JDK installation instructions.
The CLASSPATH is used by Java to find Java *.class files. Normally you'll want to leave the CLASSPATH environment variable not set.