Magic: The Gathering
Magic: The Gathering, also Magic or MTG, is a strategy card game created by Richard Garfield in 1993, and published by Wizards of the Coast.   Garfield introduced three ideas that made the game very succesful: the concept of the trading card game, the color wheel, and the mana system.  
Magic holds the title of "Most Played Trading Card Game."  The game is currently being printed in the following languages: English, French, Italian, Chinese Simplified, Portuguese, German, Spanish, Russian, Korean and Japanese. It is available for sale in the Asian, European and North America countries. The players base is mostly male, but women are catching up. 
The game is commonly played with 2 players, but can be played with more. Each player uses their own deck, which is constructed from cards they own. Players start the game with 20 life. There are several ways of winning the game, the most common being reducing your opponent to 0 life.  
There are currently roughly 12,000 unique Magic cards. The cards are sold in booster packs, preconstructed theme decks and several other packages. Because Magic keeps adding new cards, it keeps shifting what matters. The discovery process that takes days or weeks or months at another game takes an eternity in Magic. You never truly figure the game out because it keeps changing. The modular nature of trading card games means that each player has a nearly infinite number of options. It allows each player to design what kind of game experience he or she is going to have. The metagame is a major component of what makes Magic the game it is, there is are an organized play system, online resources, a library of material, and numerous communities.
Magic was conceived as a game of hidden information, as opposed to a game like chess where all of the information to make every decision is on the board at all times.  Players are required to use what limited information they have available to them, and use that to make the best decisions possible. This, combined with the inherent randomness in the way the game is played, means that there won't ever really be a certain correct way to play. 
The game may ask several skills from a player: strategic thinking, Looking for opportunities, patience, thinking ahead, factoring in variance, considering hidden information and focus. 
Trading card game
Magic is a trading card game (TCG), also called a collectible card game or customizable card game (CCG). It was the first of its kind, played using specially designed sets of cards. While trading cards have been around for longer, CCGs combine the appeal of collecting with strategic gameplay. 
The colors of Magic
Most Magic cards are one or more of five colors: White, Blue, Black, Red, and Green. The majority of artifacts don't require any specific color to cast and as such are colorless. Each color has its own philosophy and strategy. The "Color Pie" (a.k.a. "Color Wheel") is a representation of these colors, their mechanics and philosophies. 
Multicolored (or gold) cards require more than one color to cast. Multicolored cards show the strengths among the colors of the card. Hybrid cards have a split mana cost and can be cast using either of the two types of mana in the split symbol.
Mana is the primary resource for playing spells. Mana is typically drawn from lands (like the basic lands Plains, Island, Swamp, Mountain and Forest) but it an also be generated by non-land permanents and spells. Players choose whatever cards they want. In order for that to work, the game needs some way to make as many cards as possible matter. By making spells have a cost, the designers are able to make different cards important at different parts of the game. Because of this, each card now has a different reason to be considered for a deck. This diversity of card usage is a key factor in making the entire trading card game work. 
A card type is a characteristic that each Magic: the Gathering card has. Each card type has its own rules for how they are played. The main card types are: artifact, creature, enchantment, instant, land. planeswalker and sorcery. Some objects may have more than one card type (e.g., artifact creature). Additionally, cards may have supertypes or subtypes.
The first magic core set called Alpha was created by Dr. Richard Garfield and bought by Wizards of the Coast and released in 1993. Three core sets (Beta, Unlimited, and Revised) were released shortly after the Alpha release in order to satisfy the growing demand for the card game. The first expansion set, Arabian Nights, was released December 1993. It was based off of the Arabic compilation of Stories One Thousand and One Nights, and offered quotes from various stories in the compilation.  At one point in time, it was discussed that each expansion should have their name printed on the backs of the cards along with "Magic: The Gathering;" however, this idea quickly fell by the wayside in order to provide card uniformity.  Shortly afterward, the second expansion set, Antiquities, was released in the spring of 1994. Many expansion followed. Ice Age was the first large expansion, starting the typical block (originally called cycle) of one large expansion and two smaller expansions. In 2008, Wizards made a big push towards acquisition.  A sixty-fifth expansion, Khans of Tarkir, is scheduled to be released in September, 2014.
The DCI (formerly, Duelists' Convocation International) is the official sanctioning body for competitive play in Magic: The Gathering. The DCI provides game rules, tournament operating procedures, and other materials to private tournament organizers and players. It also operates a judge certification program to provide consistent rules enforcement and promote fair play. Wizards of the Coast and the DCI control the list of banned and restricted cards, which are considered too strong in particular tournaments.
In order to play in sanctioned events, players must register for a free membership and receive a DCI number. The DCI maintains a global player ratings database using the ELO rating system (Planeswalker points) and members have access to their entire tournament history online. If a member commits frequent or flagrant rules infractions, his or her membership can be suspended for variable amounts of time depending on the severity, from one month to a lifetime.
Decks and Tournaments
Tournament decks in general must have at least 60 cards. A deck may have no more than 4 copies of an individual card, besides basic lands which it may have any number. If a sideboard is used, it may contain no more than 15 cards.
Most games of Magic, especially casual ones, are played with constructed decks, made by the players before they arrive at game. There are also multiple formats that are played with constructed decks in DCI-sanctioned tournaments:
- In block constructed, players may play any unbanned cards from a single block. 
- In the Standard format, players play with a deck of at least 60 cards from the most recent core set, the most recent fully released block, and the block that is currently being released. 
- Vintage is the oldest format in the game, simply because it allows players the ability to use almost any card from any black or white bordered set.
- In the legacy format, cards from all sets are playable, though many of the cards which are restricted in vintage are banned in legacy.
- Modern is currently the newest eternal format in the game and bridges the gap between standard and legacy. The cardpool in this format is much smaller compared to either legacy, or vintage. The cardpool in this format encompasses all set from Eighth Edition on.
In the limited format, players do not play with decks they built ahead of time, but play with decks of cards from sealed booster packs, which are built at the beginning of a limited tournament before play begins. In limited formats, the minimum deck size is 40 cards.Generally, 17-19 lands and 21-23 spells are played, but there is some variance in this aspect. This format is favored by some, as it allows all players, no matter the size of their collection, to have an equal chance at doing well in a tournament.
- In the draft format, each participating player is seated around a table, usually of 8 players, and is given 3 sealed booster packs. Each player opens the first of their packs, chooses a card from it, and places the chosen card face-down on the table in front of them. The remaining cards in the pack are passed to the left, and players repeat this process with the pack just passed to them, until all the cards are chosen. The same is done with the second pack, this time passing to the right, and with the third pack, passing left again. Each player then builds a deck using the 45 cards they chose from the booster packs. Sanctioned drafts can be run with any number of boosters from any set, as long as each drafter receives the same product. The most common drafts are from the most recent block.
- In Sealed deck is a common format used at prerelease tournaments. Everyone is given the same amount of product, e.g. 6 booster packs. From that pool of cards, and adding in as many basic land as desired, each player must build a deck of at least 40 cards. Any opened cards not put in the main deck count as part of the sideboard. In sealed deck, the skill is making the best out of what you're given. 
Magic are yearly featured a several conventions:
- Gen Con (July)
- San Diego Comic-Con (August): big reveals about the fall set
- PAX (September): additional spoilers for the fall set, focused on the creative elements.
WotC's online convention, Uncon, featured several Magic tournaments and contests. 
- Richard Garfield. (March 12, 2013.) "The Creation of Magic: The Gathering", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Michael G. Ryan. (June 01, 2009.) "A Magic History of Time", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Mark Rosewater. (June 05, 2006.) "As Good As It Gets", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Mark Rosewater. (March 02, 2009.) "Magic Design Seminar: Looking Within", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Monty Ashley. (September 14, 2011.) "World Records", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Jennifer Robles. (December 11, 2012.) "The LPS and Creating Play Groups", Daily MTG, magicthegathering.com, Wizards of the Coast.
- John Carter. (December 25, 2004.) "The Original Magic Rulebook", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Jeff Cunningham. (June 30, 2007.) "Playing the Game", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Jeff Cunningham. (August 04, 2007.) "Lessons Learned", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Sam Stoddard. (March 22, 2013.) "The Nature of Secrecy", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Sam Stoddard. (September 13, 2013.) "Decisions, Decisions", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Reid Duke. (August 11, 2014.) "What is Magic?", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Mark Rosewater. (June 05, 2006.) "As Good As It Gets", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Mark Rosewater. (April 26, 2004.) "Collecting My Thoughts", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Mark Rosewater. (August 18, 2003.) "The Value of Pie", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Mark Rosewater. (May 30, 2011.) "Mana Action", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Richard Garfield. (August 17, 2009.) "The Expanding Worlds of Magic", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Mark Rosewater. (February 16, 2009.) "25 Random Things About Magic", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Mark Rosewater. (March 03, 2008.) "Assume the Acquisition", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Dan Gray. (June 01, 2009.) "Simple Rules are the Holy Grail of Magic", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Mark Rosewater. (August 05, 2013.) "Twenty Things That Were Going To Kill Magic", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Wizards of the Coast. (April 28, 2014.)Block Format Deck Construction
- Wizards of the Coast. (April 28, 2014.) Standard Format Deck Construction Block Format Deck Construction
- Mark Rosewater. (July 09, 2007.) "Signed, Sealed, and Delivered", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Magic Arcana. (September 18, 2003.) "Uncon 2003 Prize Sketches", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Magic Arcana. (November 12, 2003.) "Magic: The Gathering Inducted into Games Magazine Hall of Fame", Daily MTG, magicthegathering.com, Wizards of the Coast.