Opera (web browser) layout engine of its competitor Google Chrome. Features of the Opera web browser include private browsing, tabbed browsing, download manager, mouse gestures and browser extensions. Opera began in 1994 as a research project at Telenor, the largest Norwegian telecommunications company. In 1995, it branched out into a separate company named Opera Software. Opera was first released publicly in 1996 with version 2.10, which only ran on Microsoft Windows. In an attempt to capitalize on the emerging market for Internet-connected handheld devices, a project to port Opera to mobile device platforms was started in 1998. Opera 4.0, released in 2000, included
Google Sidewiki Google Sidewiki Google Sidewiki was a web annotation tool from Google, launched in September 2009 and discontinued in December 2011. Sidewiki was a browser extension that allowed anyone logged into a Google Account to make and view comments about a given website in a sidebar. Despite the name, the tool was not a collaborative wiki, though the comments were editable by the author. Google used ranking algorithms to determine comment relevancy and usefulness, using criteria such as users voting up and down a comment, and past user contributions. Anyone could look up a contributor's Google profile and assess their credibility.