InputStream handles byte data.
InputStream is an abstract class from which all
byte-oriented input streams are derived.
Its descendant classes are used for general-purpose input
These streams are aimed at
delivering data to a program in groups of 8-bit bytes.
The bytes can be grouped into the size necessary for
the type of data.
if a disk file contains 32-bit
data can be delivered to the program in 4-byte groups
in the same format as Java primitive type
We will be mostly concerned with