So-called mold uses its own particular shape to finish the tool of certain shapes and dimensions.
For example, to make cakes, you have to use a container to mold material into a specific shape. The materials such as flour, butter, etc. are raw materials but do not have a particular shape. Then you will use container for fixing to form them into a specified shape, and this container is a mold.

Food: cake mold pan, budding mold, Octopus dumpling mold tray, egg cake mold
Clothing: jewelry, spectacle frames, watch parts
Housing: taps, lights, windows and doors, plumbing
Transportation: airplanes, motor vehicles, bicycle parts
Education: pen sheaths, pencil cases, pen pots
Entertainment: computers, bats, mouse, CD boxes

Copper
Stainless steel (P20, NAK)
Heat treatment (SKD40, SKD61)
Aluminum alloy
Machining range:1060x630x420 mm

Simply said, it heats the plastic above the glass transition temperature, then via screw-type plunger mechanism to squeeze plastic material into mold and plastic materials will slowly cooled below the glass transition temperature, when this plastic will instantly solidify. Then open the mold, and remove the finished product.