What is the most widely used encoding scheme to represent data?

According to an official Google Report from 2010, the most widely used encoding scheme used to represent data on the Internet is UTF-8. UTF-8 surpassed ASCII as the most commonly used encoding scheme in 2008. As of 2014, UTF-8 makes up more than half of all existing Web pages.

UTF-8 was first introduced to the general public between Jan. 25 and 29, 1993, at the USENIX conference in San Diego. The design of UTF-8 allows backward compatibility with ASCII, a form of encoding that is also prevalent in Web pages on the Internet. Some encoding formats that are derived from UTF-8 include the CESU-8 and the Modified UTF-8.