What is unicode? What do you know about utf-8?

When you enter a character into a text editor or web application, the character is encoded using a set of numbers known as Unicode. When the browser receives the content of the web application, these decoded numbers are displayed on the screen. The main focus of this article is exactly these numbers and signs, and examining the question of what Unicode is and how to decode it, and finally, the topic of utf-8 will be addressed and we will answer the question of what is UTF-8.

What is UNICODE?

In response to the question, what is unicode? It should be said that the letters, numbers and symbols used in web applications are not managed in the computer in the same way as you see them. Computers only deal with numbers. So these letters and characters should be converted into a set of numbers 0 and 1 so that they are easy to manage. Therefore, there must be a single standard. Accordingly, it is determined what characters each of these numbers should display and how they should be stored on the disk. This standard is called UNICODE.

In fact, Unicode is a set of charset or character set with unique numbers, which is called Point Code. Each code point represents a single character. Accordingly, the Unicode standard specifies three types of encoding methods, allowing a character to be encoded within one or more bytes (i.e., in 8, 16, or 32 bits).

You should know that character in computer science is equal to letters and numbers in writing system.

What is encoding?

If we want to explain encode to you in one sentence, it should be said that converting data in such a way that the system has the ability to read and use it is called encoding. For example, the display of special characters on the web is considered a type of encoding. In fact, encoding is the process of converting data into a format required for a number of information processing needs, including:

  • Formulation of the program and its implementation
  • Data transfer, storage and compression/decompression
  • Application data processing, such as file conversion

ASCII code definition

For the encoding standard, which we mentioned above, the American Standards Association in 1960 introduced a 7-bit encoding method, called ASCII, which stands for American Standard Code for Information Interchange. At that time, the ASCII character set including 128 characters (7 bits) was defined, which was mostly for Latin languages.

In the 1980s, it was decided to use a full byte (i.e. 8 bits) for encoding in the ASCII character set instead of 7 bits. Therefore, the number of characters reaches 256. Based on this, the characters after 127 to 255 were also considered as reserved codes and other languages ​​were generally included in this range.

But in this range between different languages, there was no single standard and each language showed its own alphabet code. In other words, the code 200 in one language returns a different letter in another language. As a result, there was a need for a single standard to consider unique codes for each character while being compatible with all languages.

Trying to create a single character set for different languages

Initially, two independent attempts were made to create a single character set.

1- ISO-10646

“ISO-10646” was a project of the International Organization for Standardization


The next project was called Unicode, which was organized by a consortium called Unicode Consortium.

Having two types of standards was certainly not something that could be called a single standard. ISO and Unicode realized this and decided to merge in 1991.

The difference between ASCII code and Unicode

Unicode and ASCII are both standards used for text encoding. In fact, these two standards in programming make communication between different languages ​​possible.

What are Unicode encoding methods?

As mentioned above, Unicode performs coding in three ways, which are:

  • UTF-16
  • UTF-8
  • UTF-32

In fact, UTF stands for Unicode Transfer Format and means Unicode transfer format. In the following, we will answer the question of what is UTF-8

The difference between these coding methods is in the way letters, numbers and symbols are presented between the languages ​​of different countries. So that the way characters are presented in one country is different from another country.

What is utf-8?

In response to the question of what is utf-8, it was first officially introduced at the USENIX conference in 1993. Currently, UTF-8 is the most dominant character encoding method among websites. Utf-8 is a method that can encode all the available characters, or in other words, all the code points in Unicode.

UTF-8, as mentioned, is an algorithm that converts Pointcode numbers into binary so that they can be stored on disk.

For example, in the beginning, we present a code similar to the following code to a software:

1101000 1100101 1101100 1101100 1101111

The software knows that the provided data is a Unicode string based on UTF-8 and should show it to the user as text. In the first step, based on the UTF-8 decoding method, it converts the binary value into numbers and finally returns these codes:

104 101 108 108 111

The software knows that this is a Unicode string. The software assumes that each number returns one character. At this time, it translates each number to its corresponding character, the result is the word “Hello”.

As mentioned, UTF-8 is variable length and can go up to 4 bytes, but it can represent the original characters (ASCII) with one byte. Because it has a variable length, there must be a way to determine whether the character is made of one byte or multiple bytes.

Therefore, UTF-8 uses only 7 bits in the first byte and the first bit is left aside for this purpose.

Therefore, according to the ratio, 2 bytes in UTF-8 (11^2 = 2048 characters or code points) provide 11 bits, 3 bytes in UTF-8 support 16 bits (16^2 = 65,536) and 4 Byte also provides 21 bits (21^2 = 2,097,152).

However, the number of characters allowed in UTF-8 is currently “2097152”, while the latest version of UNICODE 6.0, which was released in 2010, only defines a little over a hundred thousand characters or code points.

UTF-8 has already overtaken other methods used in website text, reaching nearly 50% in 2010 and 84% in July 2015.

What are the advantages of utf-8?

  • UTF-8 is the only algorithm available for XML that does not require a BOM or encoding index.
  • UTF-8 and UTF-16 are the standard encoding methods for unicode text in utf-8 code files in html, with UTF-8 being the most widely used.
  • A UTF-8 code string can look like a simple heuristic algorithm. This feature, which most encoding methods do not have, allows UTF-8 to recognize the encoding type. This way, it avoids the common errors that occur when a system switches to a default encoding without having to add bits to it.
  • UTF-8 can encode any Unicode character type. Display files correctly with different scripts without having to choose the correct font.
  • UTF-8 uses the codes 0-127 for ASCII characters. This code, unlike other systems, does not need to increase the volume to show ski codes. This means that it can be processed in all software that supports 7-bit characters.
  • UTF-8 is self-consistent: if bytes are lost due to an error or problem, the start of the next valid character can be found and processing can continue.
  • Encoding in UTF-8 does not require mathematical operations such as multiplication and division and uses simple bitwise operations.
  • Disadvantages of utf-8
  • Characters that can be represented by one byte in other encoding methods such as ISO-8859 and WINDOWS-1252 must be represented by two bytes in UTF-8.
  • A UTF-8 converter, which is not compatible with current versions of the standard. It may take a different UTF-8-like number and convert it to Unicode output.
  • Text encoded by UTF-8 takes up more space than other systems, except for ASCII characters.

Disadvantages of utf-8

  • Characters that can be represented by one byte in other encoding methods such as ISO-8859 and WINDOWS-1252 must be represented by two bytes in UTF-8.
  • A UTF-8 converter, which is not compatible with current versions of the standard. It may take a different UTF-8-like number and convert it to Unicode output.
  • Text encoded by UTF-8 takes up more space than other systems, except for ASCII characters.
  • In UTF-8, it is possible to split a character in the middle of a code string. If the two separated pieces cannot fit together later in the sequence, this may cause the code string to be invalid.
  • Many software, such as text editors, cannot display or translate UTF-8 unless the text begins with a BOM.
  • UTF-8 takes up more space than a multi-byte encoding, which is only designed for a specific language. East Asian language encodings require two bytes for each character, while UTF-8 requires 3 bytes.

Why is UTF-8 so popular?

The reason lies in the fact that all ASCII characters are contained under a single byte in UTF-8. Therefore, it is fully compatible with old versions and is more optimal for English and other European languages ​​in terms of volume.

Because English and Western Europe are the most widely used languages ​​among Internet users, UTF-8 quickly became the most popular Unicode on the web.

What is the difference between ansi and utf 8?

ANSI and UTF-8 are both encoding formats. ANSI is a common byte format used to encode the Latin alphabet. Whereas, UTF-8 is a variable-length Unicode format (from 1 to 4 bytes) that can encode all possible characters.

What is the difference between UTF-16 and UTF-32 and UTF-8?

In explaining what is the difference between UTF-16 and UTF-32 with utf-8, it should be said that UTF-8 does not require additional space to store the English ASCII code, and it covers most Western European languages. It also requires 50% more space for Chinese, Japanese, and Korean, and 100% more space for Greek and Cyrillic.

On the other hand, UTF-16 does not need extra space for Chinese, Japanese, and Korean languages, but it needs 100% of its total space for Eskimo languages, Western European languages, Greek, and Cyrillic.

UTF-32 has a fixed length and occupies the most space.

last word

With the explanations provided about what unicode is and also what utf8 is, you can understand why UTF-8 is the most widely used coding method in the web space and its popularity is also increasing day by day. This is important even in email hosts, so that not choosing the right standard can make your emails unreadable. Keep in mind that despite multilingual websites, website compatibility with existing standards is the most important factor to consider when choosing your coding method.

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