Opera Software ASA (OSE: OPERA) is a Norwegian software company, primarily known for its Opera family of web browsers with over 220 million users worldwide. Opera Software is also involved in promoting Web standards through participation in the W3C. The company has its headquarters in Oslo, Norway and is listed on Oslo Stock Exchange. The company also has offices in Sweden, Poland, the People's Republic of China, India, Japan, South Korea, Taiwan, Czech Republic and the United States. Opera's stated vision is "to deliver the best Internet experience on any device."

Opera Software was founded as an independent company on August 30, 1995 by Jon Stephenson von Tetzchner and Geir Ivarsøy. The company was created to continue what was originally a research project at Telenor, the largest Norwegian telecommunications company.

Opera Software's first product, the Opera web browser version 2.1 for Windows, was released in 1997. Opera Software had an IPO in February 2004, and was listed on the Oslo Stock Exchange March 11, 2004.

Håkon Wium Lie (born 1965 in Halden, Norway) is a web pioneer, a standards activist, and, as of 2011^[update], the Chief Technology Officer of Opera Software.

He is best known for proposing the concept of Cascading Style Sheets (CSS) while working with Tim Berners-Lee and Robert Cailliau at CERN in 1994. As an employee at W3C, he developed CSS into a W3C Recommendation with Bert Bos. As a showcase and testbed, he integrated CSS into the Arena web browser. CSS is one of the fundamental web standards, with profound impact on typography, aesthetics, and accessibility on the web.

Along with his work on the CSS specifications, Wium Lie has been an activist for standards in general. He proposed the Acid2 test which was later developed and published by the Web Standards Project. Conversely, Wium Lie has targeted Microsoft's Internet Explorer due to its poor support for standards and argued against the use of formatting objects on the web.

In 2006, Wium Lie started campaigning for browsers to support downloadable web fonts using common font formats. As of 2011^[update], all major browser vendors have implemented web fonts this way. In 2007, Wium Lie started campaigning for the video element to make it easier to publish video on the web.