Sigma is a camera and lens manufacturer founded in Japan in 1961. They produce lenses for their own cameras as well as for alternative makes such as Canon, Nikon & Sony and are generally slightly cheaper than their competitors.

Lenses

Wide angle Suitable for landscape photography where it's important to capture as much of the scene as possible. Includes fisheye lenses	Standard Versatile lenses which span the range from wide angle through to low level telephoto. Suitable for most purposes.	Telephoto Lenses ideal for capturing an object at a distance. Ranging from low levels of zooming through to high end magnification. Ideal for nature photography.
Macro Used for taking photographs of objects at very close distances. Possible to take photos from as little as 3mm away.

Cameras

SD range Sigma has a small range of SLR cameras