Gold refining is the process of purifying gold to remove impurities and other metals. This is typically done through methods such as electrolysis, where an electric current is used to separate gold from other materials, or fire refining, which involves melting the gold and using chemicals to separate it from unwanted elements. The refined gold is then cast into bars or other forms for sale and use in various industries, including jewelry and electronics. The purity of refined gold is measured in karats or as a percentage, with 24 karats representing pure gold.