A JNLP file is created in the Java Network Launching Protocol (JNLP) format. It contains information such as the remote address for downloading a Java program (.JAR file) and the initial class to run. JNLP files are used for launching and managing Java programs over a network or on the web (e.g., an applet in a web browser).

JNLP files are saved in an XML format and can be viewed or edited with a text editor. They can be double-clicked to run the program if the Java Runtime Environment (JRE) is installed. NOTE: The JRE includes Java Web Start technology, which opens JNLP files and runs the specified instructions.