A canning jar is a glass container designed for preserving food through a process called canning. These jars typically have a wide mouth for easy filling and cleaning, and they come with a metal lid that creates a vacuum seal when processed. This sealing helps keep food fresh for long periods by preventing the growth of bacteria and mold. Canning jars are often used for storing fruits, vegetables, jams, and sauces. They are available in various sizes, making them versatile for different types of food preservation. Common brands include Ball and Mason, which are well-known for their quality and durability.