The Coin is the currency of every Mario-game. You can find them in almost every Game and they got many advantages. So you get in some games with 100 Coins 1 Up and the counter starts again. In some games you can lose coins, if you hurt yourself. There are also red coins, which are as valuable as 5 coins.

The Star is the second currency of some Mario-games. He is more valuable than the coins, but is in less games. In some Games you have to catch as much Stars as you can. The Star is also an Item, it gives you special skills, like jumping higher or running faster.
The ?-Block is an item, which is also in many games. They could be in the sky or on the ground, you can activate the blocks in the sky if you jump against them. When they are activated, they are in a dark red. There are Coins or Items in it. In Mariokart are some other ?-Blocks with another design.
The flag is the end of many levels and games. It became popular through Mario Bros. If you jump on the golden Top of it, you’ll get 1 up.

The normal Mushroom, you will grow.

1 Up-mushroom, you get a life.
Big Mushroom, you will be a giant mario and you're untouchable.

Mini Mushroom, you will contract, and you can jump higher.

Poison-Mushroom, if you touch it, you will get hurted.

Fire-flower, you will be able to throw fire-balls.

Ice-flower, you will be able to throw ice-balls..

Super leaf, with this costume, you can hurt your opponent and if you keep holding the A-button, you can stay in the air for a short time.

The golden leaf, it has got the same functions as the super leaf, but you will be untouchable.

Boomerang-flower, you will be able to throw boomerangs.

Blue Shell, you will be able to go into your shell.