Die casting is forcing molten metal under high pressure into reusuable steel molds called dies. Die casting is a economical way to produce metal components because you only need a few dies (produced by toolmakers, a skilled, highly paid position) to produce thousands of parts (usually these parts are made by semiskilled machine operators who are paid far less).
Modern pressure injection die casting was first used in 1849, by the Sturges company who used the method to make printing type. Printing type was the only thing that was die cast in this method for the next 20 years, but by 1892 many parts were being die cast including parts for such things as cash registers and phonographs.
In the early days of die casting, tin and lead was the most common alloy used (they are easy to melt). But in 1914, zinc and aluminum alloys arrived, and copper and magnesium alloys followed soon after.
Products made through die casting are everywhere. Things such as sink faucets, automotive parts , and toys such as Hot Wheels and Matchbox cars are also diecast.