The Toads are a species from the Super Mario Bros. series. While in some games they act as damsels and dudes in distress, Super Mario 64 and Super Mario 64 DS feature them as little helpers, providing Mario, Luigi, Wario, and Yoshi with tips about various ingame actions and events. Sometimes they even give them a Power Star which can't be achieved otherwise.
The Toads stay stationairy throuhout the game. This means one specific Toad will always be found at the same location, no matter how far the player has progressed in-game.