A MIDlet is a Java applet compatible with the Connected Limited Device Configuration (CLDC) and the Mobile Information Device Profile (MIDP). In general, this means applets for mobile phones.

Like other Java applets, MIDlets are provided as a JAR file, which is simply a ZIP archive containing the class files. MIDlets also contain a file called MANIFEST.MF inside a directory called META-INF. This is a plain ASCII text file with field names and data separated by a colon and a space. The information provided includes the name, version, icon, vendor, and size of the applet, as well as the class to be run. The manifest file is used to create the .JAD file which is used to install MIDlets on most mobile devices.