Malt gives beer its colour, flavour and contributes to the mouth feel of the beer. Malt is grain that has been tricked into coming to life (and then killed) in order to release it’s wonderful sugar. This sugar in combination with yeast is turned into the alcohol in beer.
Malting is the process of converting barley or other cereal grains into malt, for use in brewing, distilling and other less important life pursuits.
Malts are typically divided into either base or specialty malts. Base malts do the majority of the work in terms providing the fermentable sugar for the brew and specialty malts provide much of the flavour and colour. For instance our ‘tell me how it ends pale ale’ uses pale malt as its base (about 90% by weight) and crystal malt (about 10% by weight). Despite being only 10% the crystal malt gives the beer much of its colour and the important caramel flavours. The list of malts used for a brew is often collectively referred to as the grain bill.
Base malts include Pilsen (pilsener) malt, pale malt, wheat malt, Maris Otter, 2-Row and 6-Row. Specialty malts include Vienna malt, crystal malt, chocolate malt… There are hundreds of malts each with different characteristics depending on what you are after. Specific information can be found here on a large range of malts. This link may help you find out about a specific malt or give you a sense how malts can vary.