An ankle support or brace provides protection and support whilst healing and can also help prevent injuries in weak and unstable ankles, or when extreme demands are placed on the ankles such as in basketball.
Some will retain the heat produced by the body in a specific area and so aid the healing process.
Heat encourages blood vessels to dilate and so allows more blood to the injured area. The more blood that gets to the injured area, the more nutrients it will get and the faster it will heal. A heat retainer is easy to put on and take off and will retain the heat. It will give mild support.
If you have very weak or unstable ankles with possible permanent ligament stretching then something more substantial which will physically help prevent the ankle from turning over is required.
One option is taping. This provides excellent support, however can be difficult to do on a regular basis and expensive. An ankle brace such as those shown opposite provides more support and can prevent ankles from repeated sprains.