Nokia Lumia

Nokia Lumia, later rebranded to Microsoft Lumia, is a discontinued line of mobile devices that was originally designed and marketed by Nokia and later by Microsoft Mobile. Introduced on 26 October 2011, the line was the result of a long-term partnership between Nokia and Microsoft—as such, Lumia smartphones run on Microsoft software, the Windows Phone operating system; and later the newer Windows 10 Mobile. The Lumia name is derived from the partitive plural form of the Finnish word lumi, meaning "snow".

The series debuted with the Nokia Lumia 800 and the Lumia 710 smartphones. In April 2012, the first high-end flagship, Nokia Lumia 900, was released in the US in partnership with AT&T, backed by a major marketing push. Its later flagships included the Nokia Lumia 920, 925, and the first phablet-style model, Nokia Lumia 1520. However, its most successful model was in the lower-end, the budget Nokia Lumia 520, released in April 2013. In July 2013, Nokia introduced the Lumia 1020 with a 41-megapixel sensor, considered to be one of the most iconic Nokia handsets. One tablet computer was also released in the Lumia line, the Nokia Lumia 2520, running Windows RT.

Microsoft, the developer of Windows Phone software, purchased Nokia's mobile device business in April 2014, as a result leading to the Lumia line's maintenance being transferred to Microsoft Mobile. As part of the transition, Microsoft continued to use the Nokia brand on Lumia devices until October 2014, when it began to officially phase it out in favor of Microsoft branding, and in November 2014 announced the first Microsoft branded Lumia product, the Microsoft Lumia 535. In October 2015, Microsoft announced the first Lumia devices running on Windows 10 Mobile: the flagship Lumia 950, Lumia 950 XL and Lumia 550. The most recent Lumia device, the Microsoft Lumia 650, was announced in February 2016.

Sales decreased sharply after the introduction of Windows 10, with sales estimated to have dropped below one million units by the end of 2016. In October 2017, Microsoft's corporate vice president, Joe Belfiore, confirmed that Microsoft would no longer sell or manufacture new Windows 10 Mobile devices. The existing devices would receive bug fixes and security updates only, ending for the latest devices in December 2019. The last smartphone from Microsoft was the Surface Duo 2, under the Surface brand.

In 2024, HMD Global released HMD Skyline, a smartphone with a similar hardware design to the Lumia series, but running on Android instead of Windows Phone.

From 1998 to 2012, Nokia was the largest vendor of mobile phones in the world, which included early smartphones built on its Symbian platform. However, in recent years, its market share declined as a result of the growing use of touchscreen smartphones from other vendors, such as Apple's iPhone line and Android-based products. In 2010, its market share had declined to 28%, and in April 2012, Samsung Electronics (a prominent user of Android) ultimately overtook Nokia as the largest mobile phone vendor in the world. Nokia's CEO Stephen Elop vetoed the idea of producing Android devices, believing the company wouldn't be able to suitably differentiate its Android products from that of other vendors. In an employee memo, Elop infamously described the company as being on a "burning platform", blaming the "war of ecosystems" between iOS and Android as part of Nokia's overall struggle, and asserting that the company needed to make major changes to its operation.

In February 2011, Stephen Elop and Microsoft's CEO Steve Ballmer jointly announced a major business partnership between Nokia and Microsoft, which would see Nokia adopt Windows Phone as its primary platform on future smartphones, replacing both Symbian and MeeGo. The deal also included the integration of Bing as the search engine on Nokia devices, and the integration of Nokia Maps into Microsoft's own mapping services. Nokia had planned to use the MeeGo platform as part of its future plans prior to the announcement, although the company announced that it would still release one MeeGo device in 2011. Aligning with Microsoft had been considered a possibility by analysts due to Elop's prior employment with the company.

Nokia unveiled its first Windows Phone 7-based devices, the mid-range Lumia 710 and high-end Lumia 800, on 26 October 2011 at its Nokia World conference. Motivated by requests from the U.S. carrier AT&T for an LTE-enabled device, Nokia quickly developed the Lumia 900 as a follow-up, first unveiled at the 2012 International CES. The Lumia 900 received heavy promotion by the carrier as a flagship device, but its launch was dampened by a software bug that prevented the device from connecting to certain mobile data networks, forcing AT&T to issue credits to those who purchased the device. Upon its launch in April 2012, the Lumia 900 was listed as a top seller on Amazon.com, but online sales began to taper off by May. While not revealing further details, a Nokia representative stated that the company was "pleased with the consumer reaction, as well as the support we have received from AT&T", while AT&T's mobility chief Ralph de la Vega stated that the Lumia 900 had "exceeded expectations".