Clarified butter is butter with the milk solids and water removed. Because the milk solids are what causes butter to burn, clarified butter has a higher smoke point and can be used for high-temperature cooking. Removing the water also extends its shelf life.
To make clarified butter, melt at least one stick of butter in a saucepan over low heat. Melting over high heat creates the risk of browning or burning the butter. As the foam forms and rises to the top, spoon it off. When all the foam has been removed, turn off the heat, then either spoon out or carefully pour off the clarified butter, leaving the solids at the bottom.
This is also known as Ghee(or other names) in many south asian cuisines.