Question 1

What is an ASCII code?

Accepted Answer

ASCII (American Standard Code for Information Interchange) assigns a number from 0 to 127 to each character. 'A' = 65, 'a' = 97, '0' = 48, space = 32. It standardized character encoding for English text in early computing and is still the foundation of Unicode.

Question 2

What is the difference between ASCII and Unicode?

Accepted Answer

ASCII covers only 128 characters (English letters, digits, punctuation, control codes). Unicode extends this to over 140,000 characters covering all world languages, symbols, and emoji. UTF-8 — the dominant encoding today — is backward-compatible with ASCII for the 0–127 range.

Question 3

Why do uppercase and lowercase letters have different ASCII codes?

Accepted Answer

Historical design: uppercase letters (A=65–Z=90) and lowercase (a=97–z=122) are in separate ranges. They differ by exactly 32 — a bit that can be toggled. In binary: 'A'=01000001, 'a'=01100001. This design made case conversion simple for early processors.

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