ASCII & Unicode

ASCII, which stands for "American Standard Code for Information Interchange," is a character encoding standard that was developed in the early 1960s to represent text and control characters in computers and communication equipment.

It's one of the foundational building blocks of modern computing and is still widely used today, though it has been largely supplemented by more advanced character encoding standards like UTF-8.

Key points

• ASCII character encoding assigns a unique number to letters, numbers and other printable characters like spaces, commas and line breaks.
• Represented using 7-bit binary - 128 possible characters
• Only works for English language.

Here is an ASCII table with all the associated charaters and their denary equivalent.

ASCII is limited to representing a relatively small set of characters. It primarily includes the characters used in the English language, such as letters (both uppercase and lowercase), numbers, punctuation marks, and some control characters.

Therefore:

• It does not support characters from other languages or writing systems.
  
• It doesn't have support for emojis or other special characters.

One of the key limitations of ASCII is that it only worked with the English Alphabet. As computers were more widely available ASCII was extended to 8 bits, allowing another 128 characters. This was known as extended ASCII and included other European languages.

128 Ç  129 ü  130 é  131 â  132 ä  133 à  134 å  135 ç
136 ê  137 ë  138 è  139 ï  140 î  141 ì  142 Ä  143 Å
144 É  145 æ  146 Æ  147 ô  148 ö  149 ò  150 û  151 ù
152 ÿ  153 Ö  154 Ü  155 ¢  156 £  157 ¥  158 ₧  159 ƒ
160 á  161 í  162 ó  163 ú  164 ñ  165 Ñ  166 ª  167 º
168 ¿  169 ⌐  170 ¬  171 ½  172 ¼  173 ¡  174 «  175 »
176 ░  177 ▒  178 ▓  179 │  180 ┤  181 ╡  182 ╢  183 ╖
184 ╕  185 ╣  186 ║  187 ╗  188 ╝  189 ╜  190 ╛  191 ┐
192 └  193 ┴  194 ┬  195 ├  196 ─  197 ┼  198 ╞  199 ╟
200 ╚  201 ╔  202 ╩  203 ╦  204 ╠  205 ═  206 ╬  207 ╧
208 ╨  209 ╤  210 ╥  211 ╙  212 ╘  213 ╒  214 ╓  215 ╫
216 ╪  217 ┘  218 ┌  219 █  220 ▄  221 ▌  222 ▐  223 ▀
224 α  225 ß  226 Γ  227 π  228 Σ  229 σ  230 µ  231 τ
232 Φ  233 Θ  234 Ω  235 δ  236 ∞  237 φ  238 ε  239 ∩
240 ≡  241 ±  242 ≥  243 ≤  244 ⌠  245 ⌡  246 ÷  247 ≈
248 °  249 ∙  250 ·  251 √  252 ⁿ  253 ²  254 ■  255  

As computers became avialable worldwide, Extended ASCII was no longer sufficient and so Unicode was introduced, with up to 21 bits in total.

Here are 10 examples of Unicode characters from different scripts, symbol sets, and emoji ranges:

Example	Unicode	Name / Description
A	U+0041	Latin Capital Letter A
Ω	U+03A9	Greek Capital Letter Omega
Ж	U+0416	Cyrillic Capital Letter Zhe
א	U+05D0	Hebrew Letter Alef
م	U+0645	Arabic Letter Meem
क	U+0915	Devanagari Letter Ka (used in Hindi)
日	U+65E5	CJK Ideograph “Sun/Day”
⏰	U+23F0	Alarm Clock emoji

You can find many more examples here: 

Unicode is a character encoding standard designed to represent and handle text and symbols from virtually all writing systems in the world. It provides a unified and consistent way to encode characters and symbols, regardless of language, script, or platform.

Character Set

Unicode assigns a unique number (called a code point) to every character, symbol, and diacritic used in human writing systems, including Latin, Greek, Cyrillic, Arabic, Chinese, Japanese, and many others (including emojos!❤️ ). It aims to cover all written languages and scripts worldwide.

Code Points

Each character in Unicode is identified by a unique code point, typically represented in hexadecimal format (e.g., U+0041 for the Latin letter 'A'). Unicode currently defines over 143,000 code points, with room for expansion.

Unlike ASCII, Unicode can be represented using various bit sizes, depending on the encoding scheme chosen. The most common Unicode encoding schemes are :

UTF-8

Unicode characters in UTF-8 are encoded using 8, 16, 24, or 32 bits, depending on the specific character being encoded. This is the most common format as it is the most space efficient.

UTF-16

Unicode characters in UTF-16 are encoded using either 16 or 32 bits.

UTF-32

Unicode characters in UTF-32 are encoded using a fixed 32 bits (4 bytes) for each character. This encoding scheme provides a straightforward and fixed-length representation for all Unicode characters.