The name is derived from the Lithuanian hydronym Alytupis.

Alytus is a city with municipal rights in southern Lithuania. It is the capital of Alytus County. Its population in 2020 was 49,895. Alytus is the historical centre of the Dzukija region. The city lies on the banks of the Nemunas River. The major roads linking Vilnius, Kaunas, Lazdijai (border with Poland), and Hrodna in Belarus pass through Alytus.

Divided onto two separate entities for centuries, it consists of two parts still frequently referred to as Alytus I and Alytus II, the earlier being a smaller town and the latter forming the city centre with parks, microdistricts and industrial areas.

Alytus hosted the Art Strike Biennial between 18 and 24 August 2009 in response to Vilnius becoming European Capital of Culture for 2009. This included a demonstration and a three sided football match. The universal indoor Alytus Arena hosted the Eurobasket 2011 Group C matches in Alytus. In 2010 Alytus was awarded the Honourable Plate of the European Council.

Alytus has a museum dedicated to veterans of both the Afghan wars.

In Alytus, several Bonsai exhibitions were held with participants from European and other countries, such as Japan and the United States.

Alytus has hosted an annual Tomato tasting since 2007. Participants offer a wide variety of tomatoes and discuss the various factors which help produce a rich crop of the fruit. Alytus has an industrial company named Snaige, which manufactures refrigerators.