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There is a meta tag which has attribute charset equals to UTF-8 in an HTML template. What is it?
ASCII - American Standard Code for Information Interchange
It is a character encoding standard for electronic communication between machines. That allows communications between machines to happen.
ASCII is a 7-bit binary system. Each letter that is keyed in is converted into 7 binary numbers and sent over the wire.
With 7-bit binary, we can have 0-127.
The first 32 are for control codes.
For example:
A - 65: 10 00001
B - 66: 10 00010
a - 97: 11 00001
b - 98: 11 00010
Without the first two binary digits, A and a are just 1 which makes it easier to identify English alphabets.
Other countries, for example, Japan created multibyte encoding that can include Kanji characters.
This caused incompatibility for communications among machines. If your machine or computer can't decode a message it receives, your messages would end up being garbled.
If we use 32 bits to encode ASCII-encodable characters directly, the binary numbers will have a long list of zeros prefix. That will take 4 times more space for each English character.
Problems that were solved:
1) Get rids of all zeroes in English characters and ASCII set
2) Handle old computer systems that interpret 8 zeroes in a row as NULL and stop listening further (end of string)
3) It has to be backward-compatible. Let machines that understands only basic ASCII understands this new Unicode text.
It starts with a header that tells how many bytes that are in the current number. The number of 1s determines how many octets there are in the current number
For example:
1) First octet has 110. Two 1's mean two octet: header octet and a continuation octet. Continuation octet is marked by 10. x's are filled by the number that represents a character that is being transmitted.
110xxxxx 10xxxxxx
2) First octet has 1110. Two 1's mean two octet: header octet and a continuation octet. Continuation octet is marked by 10. x's are filled by the number that represents a character that is being transmitted.
1110xxxx 10xxxxxx 10xxxxxx
This UTF-8 system solved the 3 problems mentioned above cleverly.
Source: Computerphile on youtube
Thanks for reading!
Jun
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
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<body>
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| Unicode Homepage |
History - starts with ASCII
ASCII - American Standard Code for Information InterchangeIt is a character encoding standard for electronic communication between machines. That allows communications between machines to happen.
ASCII is a 7-bit binary system. Each letter that is keyed in is converted into 7 binary numbers and sent over the wire.
With 7-bit binary, we can have 0-127.
The first 32 are for control codes.
For example:
A - 65: 10 00001
B - 66: 10 00010
a - 97: 11 00001
b - 98: 11 00010
Without the first two binary digits, A and a are just 1 which makes it easier to identify English alphabets.
 |
| ASCII table from http://www.asciitable.com/ |
This caused incompatibility for communications among machines. If your machine or computer can't decode a message it receives, your messages would end up being garbled.
Unicode - UTF8
Unicode consortium figured out a standard to cover all the characters in the world.If we use 32 bits to encode ASCII-encodable characters directly, the binary numbers will have a long list of zeros prefix. That will take 4 times more space for each English character.
Problems that were solved:
1) Get rids of all zeroes in English characters and ASCII set
2) Handle old computer systems that interpret 8 zeroes in a row as NULL and stop listening further (end of string)
3) It has to be backward-compatible. Let machines that understands only basic ASCII understands this new Unicode text.
It starts with a header that tells how many bytes that are in the current number. The number of 1s determines how many octets there are in the current number
For example:
1) First octet has 110. Two 1's mean two octet: header octet and a continuation octet. Continuation octet is marked by 10. x's are filled by the number that represents a character that is being transmitted.
110xxxxx 10xxxxxx
2) First octet has 1110. Two 1's mean two octet: header octet and a continuation octet. Continuation octet is marked by 10. x's are filled by the number that represents a character that is being transmitted.
1110xxxx 10xxxxxx 10xxxxxx
This UTF-8 system solved the 3 problems mentioned above cleverly.
Source: Computerphile on youtube
Thanks for reading!
Jun
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