Question

(d) Explain the need of ASCII and Unicode?

Answer 1

The need? ASCII was just the initial formalized representation of characters to be stored as numerical data. Unicode came along because ASCII wasn't enough to encode a variety of languages that needed to be able to exist in the same character set (so that you didn't have to switch character sets just to display, say, Cyrillic). Unicode gives a variety of ways to encode a much much larger number of characters, the most common encoding being UTF-8.

Answer 2

Ultimately, the world to a computer is just a series of switches that are either on (have voltage) or off (no voltage). We can think of that as binary digits. Both ASCII and Unicode are standards where specific numbers are used to represent characters. ASCII (American Standard Code for Information Interchange) predates Unicode, which is more of a worldwide encoding scheme.