Before the web addresses were introduced, the computers were connected by entering the unique IP address of a machine. An IP address was the 32-bit (IPv4 system) address comprising of a string of digits.
With the steady increase in the number of computers, the scientists at the University of Wisconsin developed a protocol called the Domain Names System (DNS) to map the hard-to-remember IP addresses to the domain names that could easily be remembered like WonderfulEngineering.com.
The World Wide Web was invented in 1990 by a British scientist Tim Berners-Lee. Around one million computers were connected to the internet by 1992. Thus, in 1994, the International Engineering Task Force (IETF) published a set of standards called the Uniform Resource Locators (URLs) for the web standards. IETF was mostly made up of the US government representatives.
To ensure easier connectivity, IETF only allowed the use of uppercase and lowercase English or Latin alphabets, a few symbols, and 0 to 9 digits in the web addresses. These characters were taken from the American Standard Code for Information Exchange or the US-ASCII character set.
Given that all the internet laws were being designed by the people who spoke English, protocols for the web addresses were made accordingly.
This might have worked out fine except for the fact that more than half the 1.6 billion Internet users recorded in 2009 were of non-English origin. These users speak, read, and understand a language which uses a character set entirely different from the ASCII character set. So, the difference becomes readily apparent of you are visiting a site from an Arabic country like Egypt where the site content is entirely in Arabic except for the web address.
Thus, it did not come as a surprise when the US-based non-profit organisation, Internet Corporation for Assigned Names and Numbers (ICANN) introduced the International Domain Names or IDNs in 2009. Now, the internet addresses can consist of non-English letters like Arabic, Korean, Chinese, etc.