JSR 203 is the umbrella under which the new (for Java 7) file API (also known as NIO2) was created. JSR 203 allows to have FileSystem implementations over any storage medium which can be viewed as a filesystem from a user perspective; the JRE provides a default implementation for your local machine, but also a provider for FileSystems over zip files. Other implementations exist over FTP, DropBox, box.com, in memory and a few others.
