A traditional trivet is usually a small three-legged metal tray placed on a dining table to protect it from hot food containers. It should suspend the hot cookware or plates at least 1 inch (2.54 cm) above the surface of the table to allow air to flow underneath. Metallic designs can range from the purely functional to the ornate, although they all perform the same duty. Some trivets are custom-fitted to specific cookware, such as gravy boats or teapots.
Other materials may also be used to create a trivet. One common woodworking project uses a small wooden frame and heat-resistant ceramic tile pieces. The woodworker first creates a square framework from a denser wood like ebony, and then attaches small ceramic tiles with a heat-resistant silicone glue. One made this way can be very decorative indeed, since there are literally hundreds of different tile pieces from which to choose.
With the advent of new heat-resistant materials such as silicone, a modern trivet may not use any metal for structure. Many cooks will use oven mitts or silicone pads in place of a traditional metal tray. Any material that can absorb heat safely and protect the surface of a finished table could be considered an informal trivet. The heat generated by microwaved meals can be enough to cause serious damage to a dining table, so a protective layer should be used whenever possible.
When shopping for a trivet, consider both form and function. It can be kept on the table between meals, so some decorative elements may be appreciated. A metal trivet for casual use is usually on the plain side, although some may feature ornate designs on the legs. Ceramic ones can be very decorative, and it may be possible to find one that fits your kitchen's overall color scheme or style. Those made of silicone may be available in different colors, but they are more functional than stylish in most cases. Potholders can also be used as informal trivets, so you might find an appealing design in that area of the store.