🌐 Unicode

🌐 Universal Character Encoding

Unicode is a computing industry standard for consistent encoding, representation, and handling of text expressed in most of the world's writing systems. It provides a unique number for every character, regardless of platform, program, or language.

📝 What is Unicode?

Unicode is a character encoding standard that:

• Aims to include all characters from all writing systems of the world
• Assigns a unique code point (number) to each character
• Supports modern and historical scripts, symbols, and emoji
• Enables consistent text representation across different platforms
• Is maintained by the Unicode Consortium

🔑 Key Concepts

🔢 Code Points

A code point is a numerical value that represents a specific character:

• Expressed as U+XXXX (where XXXX is a hexadecimal number)
• Range from U+0000 to U+10FFFF
• Can represent over 1.1 million different characters
• Currently, about 144,000 characters are assigned

Examples:

• U+0041: Latin capital letter A
• U+4E2D: Chinese character for "middle" (中)
• U+1F600: Grinning face emoji (😀)

🗺️ Planes

Unicode divides its code points into 17 planes, each containing 65,536 code points:

• Basic Multilingual Plane (BMP): U+0000 to U+FFFF
  • Contains most commonly used characters
  • Includes Latin, Greek, Cyrillic, Chinese, Japanese, Korean, etc.
• Supplementary Planes: U+10000 to U+10FFFF
  • Include less common scripts, historical symbols, emoji, etc.

⚙️ Character Properties

Unicode assigns various properties to each character:

• Category (letter, number, punctuation, symbol, etc.)
• Case information (uppercase, lowercase, titlecase)
• Directionality (left-to-right, right-to-left)
• Combining behavior (how characters combine with others)
• Decomposition (equivalent character sequences)

💾 Unicode Encoding Forms

Unicode defines several encoding forms to represent code points in computer memory:

📊 UTF-8

• Variable-length encoding using 1 to 4 bytes per character
• ASCII characters (U+0000 to U+007F) use just 1 byte
• Most common encoding on the web and in modern systems
• Backward compatible with ASCII
• Space-efficient for Latin script text

📋 UTF-16

• Variable-length encoding using 2 or 4 bytes per character
• BMP characters use 2 bytes
• Characters outside BMP use 4 bytes (surrogate pairs)
• Used internally by Windows, Java, JavaScript, etc.

📈 UTF-32

• Fixed-length encoding using 4 bytes per character
• Simple mapping between code points and encoded form
• Less space-efficient but easier to process
• Used in some programming environments

🔄 Unicode vs. Earlier Encodings

Unicode addresses limitations of earlier character encodings:

Feature	ASCII	ISO-8859	Big5/GB	Unicode
Character range	128	256	~20,000	Over 140,000
Multilingual support	No	Limited	Limited	Comprehensive
Consistency across systems	Yes	No	No	Yes
Backward compatibility	-	With ASCII	With ASCII	With ASCII (UTF-8)

💻 Unicode in Practice

🔍 Text Processing

• Enables consistent sorting, searching, and comparison
• Provides rules for text segmentation (word boundaries, line breaking)
• Defines normalization forms for equivalent character sequences

🌍 Internationalization

• Allows software to support multiple languages
• Enables text rendering for complex scripts
• Supports bidirectional text (mixing left-to-right and right-to-left)

🕸️ Web Development

• HTML5 uses UTF-8 by default
• CSS supports Unicode for selectors and values
• JavaScript uses UTF-16 internally

📚 Common Unicode Blocks

Unicode organizes characters into logical blocks:

• 🔤 Basic Latin (ASCII): U+0000 to U+007F
• 🔡 Latin-1 Supplement: U+0080 to U+00FF
• 🈶 CJK Unified Ideographs (Chinese, Japanese, Korean): U+4E00 to U+9FFF
• 😀 Emoji: U+1F600 to U+1F64F (and others)

⚠️ Challenges and Considerations

🔄 Normalization

• Multiple ways to represent some characters (e.g., é can be a single code point or e + accent)
• Normalization forms (NFC, NFD, NFKC, NFKD) provide standardized representations

🎨 Rendering Complexity

• Some scripts require complex rendering rules
• Combining marks, ligatures, and contextual forms add complexity
• Proper font support is necessary for correct display

⌨️ Input Methods

• Inputting thousands of characters requires specialized methods
• Input method editors (IMEs) for Asian languages
• Virtual keyboards and character pickers for special symbols

Understanding Unicode is essential for:

• 🌐 Developing internationalized software
• 🗣️ Working with multilingual text data
• 🔄 Ensuring proper text handling across different systems
• 🌍 Supporting global users with diverse language needs

Unicode represents a significant achievement in computing, enabling truly global communication and information processing.