In the year 1795 a prize was announced by the French government for investing a way to preserve food for the use of their army. A man named Francois Appert won the prize by devising a way to keep food fresh in sealed glass bottles by placing them in boiling water. But no one could explain why the food stayed fresh when treated that way, although it did not stray fresh for very long.
Again in 1829, William Underwood began selling bottled food in Boston. Ten years later, he used a tin-coated steel can instead of the glass bottle. The cans were assembled by workers and filled with food through a hole at the top. The hole was then sealed by a drop of solder.
In 1860, another American found a better process, to store food for longer periods. He heated the food inside cans at higher temperatures. Canned food has, since then, become one of the most popular way of preserving many food items.