 Opera has undergone extensive changes and improvements, and introduced notable features such as Speed Dial.Until version 2.0, the Opera browser was called MultiTorg Opera (version 1.0) and had only a limited internal release—although it was demonstrated publicly at the Third International WWW Conference in April 1995.It was known for its multiple document interface (MDI) and 'hotlist' (sidebar), which made browsing several pages at once much easier, as well as being the first browser to completely focus on adhering to the W3C standards.