Bag sealers are handy devices used to seal plastic bags, keeping food and other items fresh for longer periods. They work by applying heat to the edges of the bag, melting the plastic slightly to create an airtight seal. This helps prevent moisture, air, and contaminants from entering, which can spoil the contents. There are various types of bag sealers, including manual and automatic models. Some are designed for home use, while others are more industrial and can handle larger volumes. Popular brands often include FoodSaver and Vacuum Sealer, which offer additional features like vacuum sealing for even better preservation.