The Red switch is one of the 4 colored switches found in Super Mario World. When the Red Switch is stomped on all the Red dotted blocks will turn into Red solid ! blocks. The Red Switch level is named "Red Switch Palace" in Super Mario World. When the level is entered it will look much like the bonus game. It should also be noted that nothing will come out of the red switch block if it is hit below, it just behaves as a normal solid block. Unlike the Yellow and Green blocks which have mushrooms and cape feathers coming out of them respectively.
It re-appears in the New Super Mario Bros. series, where they have exactly the same effect: they make dotted blocks into solid Red Blocks for a short period of time in a level.