Used to be known as Ginger Beer - my mum used to make it. You "grow" the culture in a jam jar and feed it with ginger and sugar every day. Once a week you strain it off and convert the liquid into the "beer". The culture is easy. One teaspoon of dried yeast, one teaspoon of sugar and one teaspoon of dried ginger powder. Mix with about half a pint of water. As I said, you feed it one teaspoon of sugar and one teaspoon of dried ginger per day. At the end of the week you strain the whole lot through muslin, discard or give away half the sludge and start again with the remaining half of the sludge. The liquid is diluted with water and lemon juice and bottled into strong beer bottles (The sort with screw caps are good but as Tootles says the stuff carries on fermenting and can blow the tops off if they aren't secure. Can't find the quantities of water and lemon juice at the mo, but will do some research and get back.