The history of the Opera web browser began in 1994 when it was started as a research project at Telenor, the largest Norwegian telecommunications company. In 1995, the project branched out into a separate company named Opera Software ASA, with the first publicly available version released in 1996. 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.
In February 2013, Opera Software announced that their in-house rendering engine, Presto, would be phased out in favour of WebKit. Opera 15 saw the browser being fully rewritten, with this and subsequent releases being based on Blink and Chromium.
Elektra versions
Version 2
Version 2.0, the first public release of Opera, was released as shareware in 1996.
Due to popular demand, Opera Software showed interest in programming its browser for alternative operating systems such as Apple Macintosh, QNX and BeOS. On October 10, 1997, they launched "Project Magic", an effort to determine who would be willing to purchase a copy of their browser in their native OS, and to properly distribute funds to develop or outsource for such operating systems. On November 30, 1997 they closed voting for which operating system to develop with. Project Magic then became a news column for updates for alternative operating systems until version 4.
Version 3
Opera 3 was the first version of Opera with JavaScript support, but Java was still missing. It was released for multiple operating systems on December 31, 1997.
In 1998, Opera 3.5 was released, adding Cascading Style Sheets (CSS) support and file upload capability.
Since version 3.5, Opera has supported CSS, and Håkon Wium Lie, one of the inventors of CSS, is the CTO at Opera. Up to 6.0 Opera supported most common web standards, Netscape plugins and some other recent standards such as WAP and WML for wireless devices, but its implementation of advanced ECMAScript (of which "JavaScript" is an implementation) and the HTML Document Object Model was poor.
Version 3.6 was released on May 12, 1999. The 16-bit version of Opera for Windows 3.62 is the last version to support Windows 3.x. Further releases would require Windows 95.
Version 4
On June 28, 2000, Opera 4 for Windows (Elektra) was released, introducing a new cross-platform core, and a new integrated email client.
Version 5
Opera 5, released on December 6, 2000, was the first version which was ad-sponsored instead of having a trial period. Version 5 also supported ICQ, but this was dropped from later versions.
Opera supported OS/2 for the first time, requiring WarpIN and Odin to be installed.
Opera 5.10 (April 2001) was the first version to recognize mouse gestures, but this feature was disabled by default.
Version 6
On November 29, 2001, Opera 6 was released with new features including Unicode support, and offering a single document interface as well as the multiple document interface allowed by previous versions.
First MSN.com controversy
On October 24, 2001, Microsoft blocked users of browsers other than Internet Explorer, including Opera, from accessing MSN.com. After accusations of monopolistic behavior, Microsoft lifted the restrictions two days later. However, as late as November 2001, Opera users were still locked out from some MSN.com content, despite Opera's ability to display the content had it been served.
Presto versions
Version 7
On January 28, 2003, Opera 7 was released, introducing the new "Presto" layout engine, with improved CSS, client-side scripting, and Document Object Model (DOM) support. Mac OS 9 support was dropped.
Version 7.0 saw Opera undergo an extensive rewrite with the faster and more powerful Presto layout engine. The new engine brought almost full support for the HTML DOM meaning that parts of, or a whole, page can be re-rendered in response to DOM and script events.
A 2004 review in The Washington Post described Opera 7.5 as being excessively complex and difficult to use. The review also criticized the free edition's use of obtrusive advertisements when other browsers such as Mozilla and Safari were offered free of charge without including advertisements.