Multicolored (also "multicolor", "multi-colored", "multi-color"; as opposed to "monocolored", "mono-colored" "single-colored") cards were introduced in the Legends set, and use a gold frame to distinguish them. For this reason, they can be referred to as "gold" cards.   
Multicolored cards require mana from two or more different colors to be played. Multicolored cards tend to combine the philosophy and mechanics of all the colors used in the spell's cost; examples of such cards are Quicksilver Dagger and Niv-Mizzet, the Firemind, which combine blue's ability to draw cards with red's ability to deal (direct) damage ("pinging").
More recently, two-color "hybrid" cards that can be paid with either of the card's colors (as opposed to both) were introduced in the Ravnica set, and are considered to be of both colors (202.2d). Hybrid revolve around the mechanics and philosophies that the two colors have in common. The cards are distinguished by a gradient frame with those two colors. Multicolored cards tend to be proportionally more powerful compared to single-color or even hybrid cards, because of the restriction of having to play all the colors in the casting cost.
White-Blue is slow and steady. Typical white-blue decks stall the game and let the users cast their major spells in late game.
Ravnica guild: Azorius Senate
White-Black is about gradually killing one's enemies, with white slowing the game down and black destroying opponent's creatures and drain their lives.
Ravnica guild: Orzhov Syndicate
Blue-black is related to secrets and forbidden knowledge. Blue's emphasis of information and black's solitary nature combine to create a very secretive color pair. The opponents' of Blue-Black decks often realize that they are going to lose when it is too late.
Ravnica guild: House Dimir
After combining Blue's desire for progress and red's impulsiveness, Blue-Red is a color pair that focus on innovation.
Common mechanics: Power/toughness switching, reusing instants/sorceries, time manipulation (e.g. taking additional turns), copying spells and abilities, changing targets of other spells and abilities, looting, gaining control of permanents
Ravnica Guild: Izzet League
Black's anti-sociality and Red's hedonism combine to create a very sadistic and sociopathic color pair. Black-red decks typically prefer overwhelming opponents at all cost, often at the expense of their own creatures and even their users' life total.
Ravnica Guild: Cult of Rakdos
Black-Green embodies the cycle of life and death and thrives on exploiting the cycle. Black-Green capitalize on creatures that slowly grow over time or those that have special effects when they die.
Ravnica Guild: Golgari Swarm
Red-Green is very unthinking, considering the fact that it has red's impulsiveness and green's preference for instinct over mind. Red-Green decks are typically highly aggressive and attempt to overwhelm their opponents with pure strength.
Ravnica Guild: Gruul Clans
Red-White represents enforcement of justice, as a mixture of red's readiness to take action and white's insistence in righteousness.
Ravnica Guild: Boros Legion
Green-White detests black's individualistic attitude and is the color pair of group and unity. Green-White thrives in being in groups.
Common mechanics: Vigilance, creature tokens, protecting creatures, massive creature boosting, life gain, enchantments
Ravnica Guild: Selesnya Conclave
Green-Blue is the color pair of progress. Both green and blue enjoy seeing the world evolve, although the former prefers reaching it by natural selection while the latter prefers artificial means.
Ravnica Guild: Simic Combine
Shards (or Arcs) are the sets of three colors that form an arc, or an obtuse triangle (a color and its two allies): //, //, //, //, //. In order as above, they are: Bant, Esper, Grixis, Jund, and Naya.
The so-called wedges are the five color triplets that form a wedge shape, or an acute triangle : // (Dega), // (Ceta), // (Necra), // (Raka), // (Ana).  These names come from five cycles in Apocalypse, i.e. Dega Disciple, Ceta Sanctuary, Necravolver.
- ↑ Mark Rosewater. (November 14, 2005.) "Midas Touch", Daily MTG, magicthegathering.com, Wizards of the Coast.
- ↑ Mark Rosewater. (May 18, 2009.) "Golden Oldies", Daily MTG, magicthegathering.com, Wizards of the Coast.
- ↑ Zvi Mowshowitz. (May 18, 2009.) "Top 50 Gold Cards of All Time", Daily MTG, magicthegathering.com, Wizards of the Coast.
- ↑ 4.0 4.1 Mark Rosewater. (September 08, 2008.) "Between a Rock and a Shard Place", Daily MTG, magicthegathering.com, Wizards of the Coast.
- ↑ Mark Rosewater. (June 06, 2011.) "On Wedge", Daily MTG, magicthegathering.com, Wizards of the Coast.
- ↑ Mark Rosewater. (January 23, 2006.) "Now I Know My ABC’s", Daily MTG, magicthegathering.com, Wizards of the Coast.
- ↑ Mark Rosewater. (May 13, 2013.) "Absence", Daily MTG, magicthegathering.com, Wizards of the Coast.
- ↑ Mark Rosewater. (February 02, 2009.) "Party of Five", Daily MTG, magicthegathering.com, Wizards of the Coast.