There are five different colors in Magic the Gathering,Black (swamps), Red (mountains), Green (forests), White (plains) and Blue (islands). My personal favorites are black, green and red.

All of the colors have two colors which are their 'enemies'. Red's 'enemy' colors are blue and white. Black's are green and white. Blue's are red and green. White's are red and black. Green's are black and blue.

All of the colors also have a certain type of card that they are, as far as I can tell, famous for.
Black is famous for it's 'evil' spells that do mean things to the other players and, frequently, to you as well. An example of this is the 'Lord of the Pit'. This is a 7/7 creature that is flying trample and during your upkeep you must sacrifice a creature or take seven damage.
Red is famous for direct damage, such as 'Lava Axe' which does five damage to a target player.
Green's most prominant type of card is large creatures such as 'Craw Giant' which is an 8/4 trample rampage 2.
White is great for healing spells and reducing damage. An example is 'Healing Slave' that prevents up to three damage or makes you gain three life.
Blue is good if you like flying, i can't really give an example of this because it is self explanatory plus, blue also has alot of upkeep.