Jars are generally understood to be cylindrical or approximately cylindrical containers with removable lids. Historically, jars have been used for a wide variety of purposes, ranging from storage--whether it be food and drink or human remains--to artistic and decorative purposes, to scientific experimentation. The following are a few of the most common jar types.
The Mason jar--also known as the Ball jar, fruit jar or glass canning jar--is a type of glass jar developed by John L. Mason in 1858 and used to preserve food. Mason jars were originally widely used in commercial food distribution, but have been replaced over time by more efficient mass-production techniques. Mason jars are generally sealed using a two-piece device: a lid made of glass or metal is sealed to the jar using a screw-on ring, creating a vacuum and thus ensuring the preservation of the contained food.
The Kilner Jar
The Kilner jar is another type of food-preserving jar. It typically features a metal screw-top lid and a rubber seal to ensure airtightness, although early models often used a glass plug instead of the metal lid. The Kilner jar was invented by John Kilner, who founded the John Kilner & Co. glass company in 1842, specifically to produce the jar. These jars are often used to preserve homemade jams and marmalades.
The Cookie Jar
"Cookie jar" is the colloquial name given to any manner of jar--usually ceramic, but occasionally made from glass or another material--used to store cookies, other sweets, or any edible snack item. Cookie jars can be purely utilitarian, but many, especially those made from ceramic, boast a decorative element. Cookie jars originated as "biscuit jars" in 18th century Britain, and were common in North America by 1930. Cookie jars are well-recognised in pop culture, with the term coming to be a figurative way of representing a desire, often financial, that is off-limits.
The Leyden Jar
The Leyden jar is a contraption designed to store electricity by maintaining a static electric charge between two electrodes, one on the inside of the jar and the other on the outside. Although first invented by Ewald Georg von Kleist in 1744, it was named for Pieter van Musschenbroek of Leyden, who developed it separately at least a year later. The Leyden jar was used in many pioneering experiments on electricity, and was the precursor to the modern capacitor.