The fridge.

Before mechanical refrigeration systems were introduced, people cooled their food with ice and snow. The first way to keep food frozen were holes dug into the ground and lined with wood and packed with snow and ice: this was the only means of refrigeration for most history.

The first artificial refrigeration was demostrated by William Cullen in 1748, but he didn't use his discovery for any practical purpose.

An American inventor designed the first refrigeration machine and it was built by Jacob Perkins in 1834.