Java is an object-oriented programming (OOP) language, therefore an understanding of OOP is of utmost importance. However, before you explore OOP features and techniques, you should first study Java language fundamentals.
Traditionally, computers in English speaking countries only used the ASCII (American Standard Code for Information Interchange) character set to represent alphanumeric characters. Each character in the ASCII is represented by 7 bits. There are therefore 128 characters in this character set. These include the lower case and upper case Latin letters, numbers, and punctuation marks.
The ASCII character set was later extended to include another 128 characters, such as ...