Most classes that work directly with streams are part of the java.io package. There are also a few streams classes in java.util.zip.
The two main classes are java.io.InputStream and java.io.OutputStream.
These are abstract base classes for many different subclasses with more-specialized abilities.
Although InputStream and OutputStream are abstract classes, many methods in the class library are only specified to return an InputStream or OutputStream,
not the more-specific subclass.

Click the Quiz link below to take a brief multiple-choice quiz on the basics of streams.
Stream Basics Quiz