Butter is made when lactic-acid producing bacteria are added to cream and churned to make an emulsion. It doesn't sound very enticing but the flavour of butter is hard to beat.
Butter can be bought salted or unsalted. Salt is used for preservation and for flavour but the latter also varies according to the breed of cow and its feed.
Butter is around 80 per cent fat and for this reason, many people prefer to use alternatives. Low-fat spreads are generally not suitable for baking so read packaging carefully.
Some cake recipes replace butter with a mild-tasting oil such as sunflower oil which is ideal for those with a dairy intolerance or allergy. Cakes made in this way tend to be moister and last longer but they don't have the rich, buttery taste.
Keep butter wrapped in its foil packaging or a butter dish in the fridge. Keep it away from pungent foods as it has a tendency to pick up the flavours.
For rubbed in cake mixtures, use butter straight from the fridge. For creamed cake mixtures, you'll need to take the butter out of the fridge a few hours before you are planning to use it as it needs to be soft in order to cream it together well with the sugar.
Watch this video on how to cream together butter and sugar for a light, fluffy cake: