Ericsson (Telefonaktiebolaget L. M. Ericsson) (OMX: ERIC B, NASDAQ: ERIC), one of Sweden's largest companies, is a provider of telecommunication and data communication systems, and related services, covering a range of technologies, including especially mobile networks. Ericsson is currently the world's largest mobile telecommunications equipment vendor with a market share of 35%.

Directly and through subsidiaries, Ericsson also has a major role in mobile devices and cable TV and IPTV systems. Ericsson was also the inventor of Bluetooth.

Founded in 1876 as a telegraph equipment repair shop by Lars Magnus Ericsson, it was incorporated on August 18, 1918. Headquartered in Kista, Stockholm Municipality, since 2003, Ericsson is considered part of the so-called "Wireless Valley". Since the mid-1990s, Ericsson's extensive presence in Stockholm has helped transform the city into one of Europe's hubs of information technology (IT) research. Ericsson has offices and operations in more than 180 countries, with more than 17,700 staff in Sweden, and also significant presences in, for example, Brazil, China, Finland, India, Ireland, Italy, Hungary, the UK and the US.

In the early 20th century, Ericsson dominated the world market for manual telephone exchanges but was late to introduce automatic equipment. The world's largest ever manual telephone exchange, serving 60,000 lines, was installed by Ericsson in Moscow in 1916. Throughout the 1990s, Ericsson held a 35–40% market share of installed cellular telephone systems. Like most of the telecommunications industry, Ericsson suffered heavy losses after the telecommunications crash in the early 2000s, and had to lay off tens of thousands of staff worldwide in an attempt to manage the financial situation, returning to profit by the mid-2000s.