Difference between ASCII and Unicode

Difference between ASCII and Unicode

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Updated on Feb 9, 2024 17:06 IST

Encoding schemes are methods or algorithms used to represent data in a way that can be understood by computers. They convert data into a specific format that can be transmitted, stored, and interpreted by different devices and software.


There are various types of encoding schemes, each designed for a specific purpose. Here are some examples: 

  • ASCII (American Standard Code for Information Interchange) 
  • Unicode 
  • Base64 
  • UTF-8 
  • Binary-coded decimal (BCD) 

These encoding schemes are essential in ensuring that data can be accurately and efficiently processed, transmitted, and stored by computers and other digital devices. 

In this article, we will be comparing the two most popular coding schemes: Unicode and ASCII. So, let’s get started! 

We will be covering the following sections: 

Introduction to ASCII 

The ASCII (American Standard Code for Information Interchange) encoding scheme is a widely used method for representing text in computers. Its development dates back to the 1960s when it was established as a standard for encoding characters on computers and communication equipment. 

Each character in ASCII is assigned a unique code or number from 0 to 127, represented by 7 bits. These codes include letters, numbers, punctuation marks, and special characters like line breaks, tabs, and control characters. 

For instance, the letter ‘A’ is coded as 65 in ASCII, ‘a’ as 97, and ‘@’ as 64. ASCII has limitations in that it only encodes characters from the English language, and it does not support characters with accents or those from other languages. 

Despite its limitations, ASCII is still popularly used for basic text communication as it is widely supported by computer systems and simple to use. 

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ASCII Characters 

In this section, we will discuss ASCII and its usage in electronic communication. ASCII stands for American Standard Code for Information Interchange and is a popular encoding scheme for computers. 

ASCII represents characters using integers, including numbers (0-9), uppercase letters (A), lowercase letters (A), and symbols such as semicolons (;) and exclamation marks (!). Integers are preferred for storage in electronic devices over alphabets or symbols since they are easy to store. For example, the integer 97 represents the letter “a,” and 33 represents “!,” which can be stored in memory without difficulty. 

If the ASCII value of one alphabet is known, it is possible to estimate the ASCII value of another alphabet. For instance, if the ASCII value of “a” is 97, then the ASCII value of “z” will be 97 + 25 = 122. 

ASCII uses 8 bits to encode any character, most of which are from the English language and used in modern-day programming. ASCII is also used in graphic arts to represent clip art or images using characters. 

One major limitation of ASCII is that it can only represent 256 different characters, as it uses only 8 bits. This means that ASCII cannot encode the many types of characters found in languages worldwide. Unicode was developed to overcome this limitation and extended to UTF-16 and UTF-32 to encode various types of characters. Therefore, the primary difference between ASCII and Unicode is the number of bits used to encode. 

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Decimal-Binary-ASCII Conversion Chart 

Decimal Binary ASCII
000000  NUL 
000001  SOH 
000010  STX 
000011  ETX 
000100  EOT 
000101  ENQ 
000110  ACK 
000111  BEL 
001000  BS 
001001  HT 
10  001010  LF 
11  001011  VT 
12  001100  FF 
13  001101  CR 
14  001110  SO 
15  001111  SI 
16  010000  DLE 
17  010001  DC1 
18  010010  DC2 
19  010011  DC3 
20  010100  DC4 
21  010101  NAK 
22  010110  SYN 
23  010111  ETB 
24  011000  CAN 
25  011001  EM 
26  011010  SUB 
27  011011  ESC 
28  011100  FS 
29  011101  GS 
30  011110  RS 
31  011111  US 
32  100000  Space 
33  100001 
34  100010  ” 
35  100011 
36  100100 
37  100101 
38  100110 
39  100111  ‘ 
40  101000 
41  101001 
42  101010 
43  101011 
44  101100 
45  101101  – 
46  101110 
47  101111 
48  110000 
49  110001 
50  110010 
51  110011 
52  110100 
53  110101 
54  110110 
55  110111 
56  111000 
57  111001 
58  111010 
58  111010 
59  111011 
60  111100 
61  111101 
62  111110 
63  111111 
64  1000000 
65  1000001 
66  1000010 
67  1000011 
68  1000100 
69  1000101 
70  1000110 
71  1000111 
72  1001000 
73  1001001 
74  1001010 
75  1001011 
76  1001100 
77  1001101 
78  1001110 
79  1001111 
80  1010000 
81  1010001 
82  1010010 
83  1010011 
84  1010100 
85  1010101 
86  1010110 
87  1010111 
88  1011000 
89  1011001 
90  1011010 
91  1011011 
92  1011100   
93  1011101 
94  1011110 
95  1011111 
96  1100000 
97  1100001 
98  1100010 
99  1100011 
100  1100100 
101  1100101 
102  1100110 
103  1100111 
104  1101000 
105  1101001 
106  1101010 
107  1101011 
108  1101100 
109  1101101 
110  1101110 
111  1101111 
112  1110000 
113  1110001 
114  1110010 
115  1110011 
116  1110100 
117  1110101 
118  1110110 
119  1110111 
120  01111000 
121  01111001 
122  01111010 
123  01111011 
124  01111100 
125  01111101 
126  01111110 
127  01111111  DEL 

Introduction to Unicode 

Unicode is a character encoding standard that is used to represent text from many writing systems in the world. It can be thought of as a superset of ASCII, as it includes all ASCII characters and many additional characters from other scripts, such as Greek, Arabic, Chinese, and so on. The Unicode standard is designed to be comprehensive, so that it can support all of the characters needed for any writing system, as well as symbols and special characters for use in mathematics, music, and other fields. 

Unicode uses a code point system to assign a unique number to each character, which is typically represented in hexadecimal notation, rather than the decimal notation used in ASCII. For example, the Unicode code point for the letter “A” is U+0041, while the code point for the Greek letter alpha is U+03B1. Unicode characters can be encoded using several different methods, including UTF-8, UTF-16, and UTF-32, which use different numbers of bytes to represent characters. 

One of the major advantages of Unicode is that it can support a wide range of languages and scripts, allowing users to communicate and exchange information in multiple languages without the need for different encoding systems. This has helped to make the internet and other global communication systems more accessible and inclusive for people around the world.  

Unicode Characters 

Unicode Consortium is a non-profit organization responsible for maintaining the Universal Character Set, a standard for encoding and representing characters in electronic devices.  


The IT industry relies on Unicode as a way to represent an extensive range of characters, including mathematical symbols and texts in multiple languages such as Devanagiri, Latin, Greek, Cyrillic, and Armenian. It is also able to represent texts written from right to left, such as Hebrew and Arabic, making it one of the only encoding schemes that can support characters from around the world. 

The Unicode Transformation Format, or UTF, is the type of Unicode encoding scheme used. UTF encoding schemes are categorized by the number of bits they use to represent characters, with UTF-7, UTF-8, UTF-16, and UTF-32 utilizing 7, 8, 16, and 32 bits, respectively. Unicode is essential for internationalizing and localizing computer software and is used for various applications such as operating systems, XML, and Java programming.  

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Relationship between ASCII and Unicode 

ASCII and Unicode are related encoding schemes used to represent characters in electronic devices. ASCII is a subset of Unicode and represents a limited range of characters primarily used in the English language. In contrast, Unicode is a more comprehensive encoding scheme that can represent characters from multiple languages and scripts, including mathematical symbols and other specialized characters. 

ASCII uses eight bits to encode characters, allowing it to represent only 256 characters. In contrast, Unicode can represent over one million characters with its various encoding schemes that utilize different numbers of bits for character representation. 

Because Unicode can represent characters from different languages and scripts, it is a more flexible and versatile encoding scheme than ASCII. Most modern computer systems use Unicode encoding schemes, allowing for the creation and use of software and applications that support multiple languages and character sets. 

Difference between ASCII and Unicode 

Here is a comparison table of the main differences between ASCII and Unicode: 

Feature  ASCII  Unicode 
Full name  American Standard Code for Information Interchange  Universal Character Set 
Supported languages  Primarily English  Multiple languages and scripts 
Number of characters supported  256  Over 1 million 
Number of bits used for character representation  7 or 8  8, 16, 32, or more 
Characters represented  Primarily letters, digits, and symbols used in English  Letters, digits, symbols, and characters used in multiple languages and scripts 
Compatibility with modern systems  Limited, as it cannot represent characters from non-English languages  Widely used in modern systems, including software and applications 
Use cases  Limited to representing English text in early computer systems  Used for a broad range of applications, including text processing, programming, and web development 

Overall, while ASCII is a simpler encoding scheme that is limited to the representation of English text, Unicode is a more versatile and widely used encoding scheme that can represent characters from multiple languages and scripts. The Unicode standard has enabled the creation of multilingual software, allowing for greater communication and global collaboration. 

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In summary, encoding schemes such as ASCII and Unicode play an essential role in the way computers process and display text. ASCII is a simple encoding scheme that can represent a limited set of characters used in English, while Unicode is a more versatile and widely used encoding scheme that can represent characters from multiple languages and scripts. As the world becomes more globalized, the use of Unicode has become increasingly important for enabling communication across different languages and cultures. Understanding the differences between these encoding schemes can be helpful for developers, software engineers, and anyone  

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Author: Prerna Singh

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