There are 5 basic land cards, and many land cards of different varieties. The picture at the right is all 5 basic land cards.
The picture at the right is a picture of a non-basic land card.
Islands produce blue mana, swamps produce black mana, forests produce green mana, plains produce white mana, and mountains produce red mana.
You tap land cards by turning them horizontal. When you tap a land you add one of that color mana to your mana pool.
You must tap land cards to summon creatures and other cards onto the field.