A thermos is a container designed to keep liquids hot or cold for extended periods. It typically consists of two layers of material, often glass or stainless steel, with a vacuum in between. This vacuum acts as an insulator, reducing heat transfer and maintaining the temperature of the contents. Thermoses are commonly used for beverages like coffee, tea, and soup. They come in various sizes and designs, making them convenient for travel, picnics, or daily use. The brand Thermos is one of the most recognized manufacturers of these insulated containers.