The Mushroom Kingdom:
Mario and co. have to have their adventures somewhere. This is where the Mushroom Kingdom comes into play. Most of the inhabitants of this kingdom are Toads (Left). Their princess who doesn't seem to have a dad, so wouldn't that make her the queen? Her name is Peach Toadstool. She's always getting kidnapped by Bowser, and then Mario and Luigi have to go save her. Sometimes Mario goes by himself. The Mushroom Kingdom also has some items that Mario, Luigi, etc. can use to help them throughout their adventures. Here's a list of some of them: Super Mushroom, Mini Mushroom, Mega Mushroom, Fire Flower, and Star. The Super Mushroom allows the small, vulnerable Mario to grow back to his normal self. The Mini Mushroom does the opposite, but still helps. Mini Mario is still vulnerable, but he can get to small areas, jump higher, can run on water, and can give access to secret worlds. The Mega Mushroom makes Mario HUGE. He is invincible, but it only lasts a little bit. The Fire Flower lets Mario shoot fireballs that bounce off the ground. The Star makes Mario invincible and can kill enemies upon touching them. He also get faster, but resist the urge to speed through the level with this item, as you will probably fall into a pit and die. Usually, there are 7 to 8 different worlds. There is usually a very green and plain-like world, a desert world, an ice world, a jungle world, a mountainous world, a water world, a sky world, and a volcanic world. It usually changes every game.
Map:
Toad:
Toad is the supporting character in the Mario games, and he is mostly playable these days. In SMB (Super Mario Bros.), he would always give you a helpful hint by saying "THANK YOU MARIO! BUT OUR PRINCESS IS IN ANOTHER CASTLE!". He even gives you some stars in Super Mario 64. Some people think that Toad's head looks like a Super Mushroom, but the colors are reversed.
Yoshi:
Yoshi is very coveted in the Mario platformers. He can get extra air time by doing his signature "flutter jump". Some people say he's a dinosaur, others may say otherwise. He can eat enemies and even shoot fireballs in older games. He even comes in different colors! Their abilities aren't any different. Yoshi has even starred in a few games, like the Yoshi Story, or Yoshi's Island series. There is a game coming out sometime in 2014 called "Yarn Yoshi".