Opera is a web browser which has been around, in some form, since 1995. It is currently a Chromium-based browser with features like a built-in cryptocurrency wallet, support for non-standard emoji crypto domains (?), and messaging apps like Facebook Messenger, WhatsApp and Telegram baked directly into the UI. Since 2016, Opera has been owned by a consortium of Chinese investors. It is currently the fifth-most used browser in the world, with a market share of 2.5%.
The original Opera Software was founded in Norway in 1995. The Opera browser was first publicly released in 1996, and in its earliest versions was paid software; at the end of a free trial, you had to pay up to keep using the browser. Version 5.0 (released in 2000) marked the end of the obligation to pay, but instead displayed advertisements integrated into the UI unless/until you paid a fee to make them go away. In 2005, with version 8.5, they removed the ads entirely and Opera became freeware software. Opera’s revenue stream became the money they received from Google to use that as their default search engine.
A lot of browser features that were such good ideas that they ended up winding their way to basically every mainstream browser, were actually innovations of Opera’s. These include tabbed browsing, pop-up blocking, the ability to re-open your last-closed tab, the “Speed Dial”, and private browsing. They were also pretty early (in 2007) to release a synchronisation feature, “Opera Link”, that let you share your bookmarks, notes and so on across different devices.
The only version of Opera I’ve ever used myself was version 9, some time around 2006–2007. Wikipedia has a screenshot of what it looked like under Linux (which was the operating system I was using at the time too, incidentally). The browser didn’t win me over from Firefox, which was otherwise my daily driver, for long, but I remember liking it well enough (a lot more than Internet Explorer 6 which I had to use at school 😛).
Between 2003–2013 Opera used a rendering engine that they called Presto, which was unique to them. In 2013 it was announced that they would be moving to WebKit, and indeed to building their browser over a Chromium base. In doing this they gave up most of the “power user” features (like UI customisation) that much of their userbase really liked. They followed this up with some other unpopular decisions – in 2014 they deleted the My Opera community website, and in 2015 they removed the basic feature of bookmarks. (They put bookmarks back later, because that was ridiculous.)
Many of the original/long-term Opera Software workforce, including its cofounder, were angry about these moves and responded by creating the new browser Vivaldi. While also a Chromium-based browser, Vivaldi is otherwise an effort to recreate what was great about the original Opera, with a high degree of UI customisability for power users, features like tab stacking, mouse gestures and integrated email and feed reader clients, and a community cohered around a community website.
Opera itself has been embroiled in some controversies in recent years. Probably the worst is reports they were offering predatory loans to people in developing countries , with interest rates in the hundreds of percent per annum. Another issue is Opera’s built-in “VPN”, which is actually just a web proxy, and doesn’t work very well for a lot of people. Some people feel like this non-VPN is overselling how much privacy it can actually provide. A third issue is ads – Opera will display “promotional notifications” and insert “promotional Speed Dials and bookmarks” into your set-up by default, unless you turn preferences for that off (and allegedly even if you have turned those preferences off sometimes, especially in the mobile app).