A control deck is a term for a deck of (usually sixty) cards that aims to control the opponent's cards and progression with, ideally, the end result where one has full control of everything that is done during the game. Control decks are very powerful and present in virtually every format in the game.     
Aspects of control
- In order to reach the point of total control, one needs many resources and access to many cards and
- Generally, if one's opponent can play more spells and threats than one can respond to, pure Control decks can have difficulty recovering. Due to this, most control decks have two major things in common:
- Continual card drawing is a major aspect in control decks, as it keeps one's resources consistently available.
- The vast majority of cards that are not win conditions or card drawing spells are spells that react to any threat one's opponent can play, so that you can, ideally, respond to everything.
Control decks intend to collect resources and defend themselves until they gain total control of the game. At this point they play a threat and continue to control the opponent until the threat kills them. The manner in which these control decks defend themselves is most often how they are defined.
Because control decks are defensive in nature, they often need to adopt elements of Aggro decks or Combo decks in some metagames. Some control decks use combos to win rather than the traditional few threats, but not many; the average control deck uses so many control spells that there's little room to support an effective combo. When a Control deck adopts some aggro elements, they usually use efficient creatures or spells that gain tempo early in the game. Most Control decks that need to adopt certain elements of combo or aggro decks are forced to do so in a certain metagame where most other decks win very quickly (due to very powerful combos or extremely effective aggro creatures). Thus, the common long-term plan of winning with Control becomes too elaborate and ineffective early on.
The classic control deck, blue/x control utilizes Counterspell and its like to counter threats while increasing its land base in order to use its own limited number of threats.   While pure U (MUC) decks are rare in standard, UW and UB control are almost always present in standard formats, white offering board sweepers like Wrath of God and stall cards like Moat, Humility, and more recently Timely Reinforcements, and Black offering creature removal like Doom Blade and discard/disruption in the form of cards like Duress.
Land Destruction / Land Lock
There are two basic types of cards in Magic: lands, and spells. Land destruction decks focus on depriving the opponent of this critical resource. It hits lower on the food chain than Counterspell decks, and is thus easier to play; without lands, after all, your opponent can't cast anything, rendering counterspells unnecessary. Classic spells include Sinkhole, Armageddon, and Strip Mine. Small-creature decks, particularly White Weenie, are designed to be most effective in the early parts of the game, and therefore can run successfully on only a few lands and are thus less threatened. Land destruction has not been particularly viable as of late, as a consequence of Wizards of the Coast's conscious decision to keep the archetype from being viable, since their market research shows most players don't enjoy playing against it.
Black uses its discard effects like Duress or Thoughtseize to prevent troublesome cards from ever entering play. It also kills creatures very efficiently and can access large amounts of mana with cards such as Cabal Coffers. However, mono-black has problems dealing with artifacts and enchantments and thus requires colorless removal such as Oblivion Stone to handle them.
A prison deck is a style of control deck that attempts to establish a "lock" which prevents the opponent from interacting at all, such as preventing them from drawing useful cards, countering every spell, or not letting an opponent untap. For example, Jace, the Mind Sculptor alone can be a temporary lock with his first ability, at least long enough to activate the ultimate and seal the game.
Other popular locks include Counterbalance with Sensei's Divining Top to alter the top of the library as required. One of the oldest and then more popular prison decks at the time created a lock down on the board between Stasis and Kismet. Turbo Stasis would attempt to continually draw Islands or temporarily sacrifice a Stasis to Despotic Scepter to untap all of the own permanents, only to play another during the turn. Another Stasis lock would use Chronatog to skip all own turns, thus also preventing Stasis from leaving play, and have the opponent draw until he can draw no more and die.
- Ben Rubin. (March 17, 2007.) "Your First Control Deck", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Jeff Cunningham. (May 05, 2007.) "Introduction to Inevitability", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Jeff Cunningham. (June 02, 2007.) "Playing Against Control", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Aaron Forsythe. (April 01, 2005.) "Out of Control", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Aaron Forsythe. (April 01, 2005.) "Out of Control (2)", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Randy Buehler. (April 12, 2002.) "Asking Permission", Daily MTG, magicthegathering.com, Wizards of the Coast.
- Randy Buehler. (April 19, 2002.) "Counterspell Conundrum", Daily MTG, magicthegathering.com, Wizards of the Coast.