One the oldest camera
brands, very famous for the quality of its lens
es (more than one lens maker, including Zeiss
, makes lenses for Leica: opinions are diveded as to whether Zeiss or Leica lenses are better).
It is a German brand, made by Leitz. The Leica rangefinder (in 135 format) was what started photojournalism, but the cameras have always been popular among every kind of serious photographers. The rangefinder was developed from a protoype by Oscar Barnak.
Why do I say serious ? Mostly because Leica rangefinders are obscenely expensive, just like Leica lenses. They are also considered difficult to use. But, they are very reliable, light and silent, which makes them very good for travel photography.
Henri Cartier-Bresson used a Leica all his life, and he did know a thing or two about photography.
Leica also makes reflex cameras, which are supposed to be (again) very good and expensive.
Leica cameras are also collectible objects, and the USSR produced a whole lot of Leica clones, like the Zorki. The first Russian Leica knockoffs where made with tools and patterns obtained as war spoils after WWII.
With thanks to mintbeetle for corrections