What is the Difference Between Unicode and ASCII​?

Have you ever wondered why some characters display perfectly on one device but appear differently on another, becoming gibberish? The simple answer is you're observing fundamental differences between different character encoding systems.

ASCII and Unicode are two different character encoding systems used for interpreting how computers interact with and store textual content. Moreover, today they are used for dynamic purposes in the digital world.

ASCII is an abbreviation for American Standard Code for Information Interchange. The encoding took its first real form in the 1960s, and it became one of the first systems to be standardized. It covers the lowest level of computing, using 7 bits of character representation for 128 combinations. This system covers basic English letters in both upper and lowercase, as well as the 0-9 numerical values, common punctuation characters, and control characters used for text formatting.

ASCII predominantly caters to the basic functionalities of computing, where text written would only require English characters, standard keyboard symbols, and device controls. If you were to type the letter "A", ASCII would save it as the number 65. Similarly, an exclamation would be saved as 33 in the ASCII system. This system worked perfectly within its limited range, but as computers became increasingly universal, the English-centric ASCII design became increasingly problematic.

ASCII would struggle to represent elements of character systems in languages such as Spanish, French, Arabic, and Chinese. It would further break apart because Chinese alone has more than a thousand characters. The 128-character limit was no longer sufficient to support the global exchange of text, resulting in errors, missing characters, or unreadable symbols when users attempted to display non-English text.

In order to solve these exact problems, the Unicode system, a universal character encoding system designed to cover every character, symbol, and script used in the world, was developed. Unlike ASCII, Unicode can utilize a significantly more extensive range than just 7 bits, allowing for over a million possible character identifiers. This vast range can not only represent the Latin alphabet but also Greek, Cyrillic, Arabic, Chinese, Japanese, emojis, and many more. For example, the letter "K," which is stored as 75 in ASCII, is still stored as 75, but characters from different writing systems now coexist without any conflicts. You can try executing some examples of your choice using the ASCII converter.

Supporting various encoding forms, like UTF-8, UTF-16, and UTF-32, Unicode offers a good balance between memory efficiency and compatibility. UTF-8, for instance, is primarily used on the web because of its backward compatibility with ASCII while allowing seamless inclusion of other scripts, whereas more advanced encoding forms like UTF-16 and UTF-32 are commonly used in operating systems, programming environments, and applications that handle large-scale text processing, such as databases, text editors, and software requiring efficient manipulation of multilingual content.

You can find the key differences between ASCII and Unicode in the table below:

In short, ASCII is now considered a subset of the Unicode character set. While ASCII laid the foundation for text representation, Unicode has built the bridge to a truly global, multilingual digital world. So next time your emoji shows up correctly across devices, you can thank Unicode for solving the limitations of ASCII.