This directory is for Android .jars. There are 4 types of jars that are supported: == Input Jar and Embedded Jar == This is the jar that bindings should be generated for. For example, if you were binding the Google Maps library, this would be Google's "maps.jar". The difference between EmbeddedJar and InputJar is, EmbeddedJar is to be embedded in the resulting dll as EmbeddedResource, while InputJar is not. There are couple of reasons you wouldn't like to embed the target jar in your dll (the ones that could be internally loaded byfeature e.g. maps.jar, or you cannot embed jars that are under some proprietary license). Set the build action for these jars in the properties page to "InputJar". == Reference Jar and Embedded Reference Jar == These are jars that are referenced by the input jar. C# bindings will not be created for these jars. These jars will be used to resolve types used by the input jar. NOTE: Do not add "android.jar" as a reference jar. It will be added automatically based on the Target Framework selected. Set the build action for these jars in the properties page to "ReferenceJar". "EmbeddedJar" works like "ReferenceJar", but like "EmbeddedJar", it is embedded in your dll. But at application build time, they are not included in the final apk, like ReferenceJar files.