Originally Posted by DJMcCarthy12
Classes: A file containing the syntax to create and interact with an object. Each class is "generally" in its own file
Package: The generic name given to a folder holding one or more classes. You may have none, one, or more than one packages inside a project or jar file.
Library: Think of a library as a package (or package containing packages) ..... (or packages containing packages containing packages, etc) that is not meant to be run as a program, but is meant to be used in different programs. A library is intended to hold code frequently used so it only has to be written once. Java's AWT is a library containing packages of classes useful in making and displaying windows. Swing is another popular package. There are many others provided, or you can invent your own, but basically it is just a way to organize your classes inside folders.