Businesses in the manufacture of beer produce alcoholic drinks by brewing and fermenting ingredients such as malted barley, hops, yeast and water. Production commonly involves milling and mashing the grain, separating the sugary liquid, boiling it with hops, cooling it, and adding yeast for fermentation. The beer may then be conditioned or matured before it is filtered, carbonated and prepared for sale. Methods and recipes vary, resulting in different strengths, colours, flavours and styles, including ales, lagers, stouts and low- or no-alcohol beers. Manufacturers may brew in small batches or operate larger-scale production facilities. Their work can include developing recipes, sourcing ingredients, monitoring quality and consistency, and packaging finished beer in bottles, cans, kegs or casks. Some breweries also provide contract brewing or packaging services for other businesses.