logo
logo
Back to Blogs
created 23 days ago

Character Sets Explained – ASCII & Unicode (O Level Computer Science 2210 / IGCSE 0478)

What Is a Character Set?

A character set is a system that allows computers to represent letters, numbers, and symbols using binary codes.

Since computers only understand binary (0s and 1s), each character must be converted into a binary number.

Examples of characters:

  • Letters (A, B, C)

  • Numbers (1, 2, 3)

  • Symbols (!, @, #)

Each of these characters has a unique binary code.

ASCII (American Standard Code for Information Interchange)

ASCII is one of the earliest character encoding systems used by computers.

It assigns a unique number to each character.

Example:

CharacterASCII ValueA65B66C67a97149

Example in binary:

A = 01000001

ASCII usually uses 7 bits or 8 bits to represent characters.

computer ol

Limitations of ASCII

ASCII works well for basic English characters, but it cannot represent:

  • Many international languages

  • Special symbols

  • Emojis

Because of this limitation, a more advanced system was developed.

Unicode

Unicode is a modern character encoding system that supports a much larger range of characters.

Unicode can represent:

  • Many languages (Arabic, Chinese, Urdu, etc.)

  • Mathematical symbols

  • Emojis

  • Special characters

Unicode uses more bits per character, which allows it to store many more characters than ASCII.

computer ol

ASCII vs Unicode

FeatureASCIIUnicodeNumber of charactersLimitedVery largeLanguages supportedMostly EnglishMany languagesBits used7 or 8 bitsVariable (often 16+ bits)UsageOlder systemsModern systems

Unicode is widely used in modern computers, websites, and smartphones.

Why Character Sets Are Important

Character sets allow computers to:

  • Display text on screens

  • Store written information

  • Send text messages

  • Display web pages

Without character sets, computers could not display human language.

Exam Tip (2210 / 0478)

Students are often asked to:

  • Define character set

  • Explain ASCII

  • Explain Unicode

  • Compare ASCII and Unicode

Always mention:

  • ASCII supports fewer characters

  • Unicode supports many languages and symbols

Practice Question

Explain one advantage of Unicode over ASCII.

Answer

Unicode can represent a much larger range of characters and languages, while ASCII is limited mainly to English characters.

Learn Computer Science with IVY Online

Prepare for:

  • Cambridge O Level Computer Science (2210)

  • Cambridge IGCSE Computer Science (0478)

with IVY Online.

Our courses include:

  • Programming practice

  • Past paper solving

  • Exam strategies

  • Concept-based learning