Sink grids protect sinks from scratches, dings and dents. Since the sink grid holds the dishware slightly above the sink, pots and pans can't damage whatever surface your sink may be made of.
Sink grids allow cooks the benefit of a ready-made area to prepare vegetables or meats. Since the grid rests slightly higher than the sink itself, food contamination from dirty sink water is less likely to occur.
Sink grids can fit almost any kind of sink, ranging from single- or double-bowl sinks to kitchen sinks of any configuration. Some companies will manufacture sink grids for their own sinks or custom-design sink grids for customers.