Draught beer generally refers to beer that is hand pumped
from a barrel (a keg or cask) and served in glasses, usually in a pub or bar
(see article: ‘Family Brewers’ for more information on ‘cask beers’). These
days canned beer may be referred as draft beer, especially if it contains a
‘widget’ device, which releases carbon dioxide and creates a ‘head’ on the beer
once poured.

The precise definition of a draught beer is open to wide
interpretation, with purists arguing that a draft beer must be served direct
from a keg at source, direct for consumption. In this case, both draught beer
that is then bottled, and canned beer that is pressurised using a widget do not
qualify as draught beer.

Draught beer is generally unpasteurised (which means that
it has not been sterilised) and for that reason must be consumed in a certain
amount of time before it goes off. If a pint has gone off, you would be sure to
know as beer is made, after all from plant matter, and rotting plant matter
tastes bad!

There are occasional allegations that a pub is
‘watering down’ its beer in order to make extra profit. As unscrupulous as some
landlords are (yes, they do have to make a living!), draught beer is very
unlikely to be watered down. Piercing a barrel pressurised with carbon dioxide
(as many of them are), in order to insert water into it would be costly and
very dangerous.