Preconstructed theme deck
Constructed by Wizards of the Coast, preconstructed theme decks are a type of Magic product composed of specific non-random sets of cards that are sold in their own packaging along with each core set and expansion.  The very first preconstructed theme decks were released in the Rivals Quick Start Set.
Theme decks from expansion sets may contain any card printed in that specific block as of that expansion set.
Preconstructed theme decks were first introduced for the Tempest expansion set and contained 60 cards (including 3 rares and 12 uncommons). The amount of lands and common cards could differ. For most expansions there were four of these decks, which were simply advertised as theme decks. They could be mono-colored and bi-colored.
Adjustement of rarities
From Urza's Saga onwards, the theme decks contained 2 rares and 13 uncommons. Urza's Saga was also the first expansion set to have a three-color theme deck. Radiant's Revenge is the only theme deck with both rares being artifacts.
Invasion was the first expansion set to have a five-color theme deck.
New package design
Onslaught theme decks introduced a new design on their cardboard box that quickly showed the colors used to build the deck.
Change to intro packs
From the Shards of Alara set onwards, theme decks connected to expansions are referred to as intro packs, to better reflect the nature of these products, as they introduce newer players to Magic: The Gathering and older ones to new expansions, with their novel mechanics. The decks were now made from a card pool composed of the most recent core set and the cards from the current block. Intro decks follow a number of design rules.   Intro packs initially consisted of 41 cards featuring a foil rare, a booster pack, a strategy insert for the deck and a Magic "learn to play" guide.
Adjustment of size
Following the example of Magic 2011, with Scars of Mirrodin the size of 41 cards in the Intro Packs changed to 60 cards, like the old theme decks, but still included the booster pack. The card pool was still restricted to the current block.
With Return to Ravnica, the Intro Packs increased to contain 2 booster packs.
Alternate art face cards
Change to Planeswalker decks
As announced in 2014 intro packs, fat packs and Deck Builder's Toolkits would be refigured to accommodate starter level players after the introduction of the Two-Block Paradigm.  It turned out that, starting with Kaladesh, Intro packs were replaced by Planeswalker Decks which contain four cards which are not available in the associated set.
Portal did not contain theme decks, but Portal Second Age and Portal Three Kingdoms contained five and three decks respectively. Each of these decks contained three rares. Starter 1999 contained five theme decks, each with two rares. All of them were mono-colored.
Theme decks from Core sets are only made with cards from that core set, while theme decks from expansion sets have cards from that set's block.
Theme decks for Core sets were introduced with 7th Edition, after the discontinuation of the Starter-level sets. They contained two rares and five uncommons with a total of 40 cards. Early Core Sets contained only mono-colored theme decks.
Change to intro packs
From the Magic 2010 onwards, theme decks connected to core sets were referred to as intro packs, as well. Magic 2010 also contained the first dual-colored Core set theme decks. The Core Set intro packs now had the same content as expansion Expansion intro packs (a ready-to-play 41-card deck featuring a foil premium rare, a sealed 15-card booster pack, a strategy insert and "learn to play" guide).
Adjustment of size
With the Magic 2011 Core Set, the size of 41 cards in the Intro Packs changed to 60 cards, but still included the booster pack.
With the Magic 2013 Core Set, the Intro Packs increased to contain 2 booster packs.
This product was discontinued after the core sets were retired.
The Duel Decks contain two theme decks and a total of eight rares.
Starting with Mirrodin Besieged Wizards of the Coast also designed competitive Standard-legal decks, called event decks, for expansions and Core Sets. Although released simultaneous with new sets, they could contain cards outside of the current block or core set, as long as they were legal. Initially each set had two event decks.
Reducing to one
From Dragon's Maze onwards each set only featured one event deck.
In 2018, Wizards of the Coast will take another try at competetive preconstructed decks. These are called challenger decks. These are intended to be very strong and feature many rares, as well as at least two mythic rares. For Challenger Decks, Magic R&D changed its design process so that they could build them close to release.
Masters Edition II
Mirage block (MTGO)
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- Wizards of the Coast. (June 2, 2008.) “Changes as of Shards of Alara”, magicthegathering.com, Wizards of the Coast.
- Mark Rosewater. (January 12, 2011.) “Design Challenge #5: "Introductions Please"”, magicthegathering.com, Wizards of the Coast.
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- Wizards of the Coast. (November 7, 2014.) “PAX Australia Magic Panel”, magicthegathering.com, Wizards of the Coast.
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- Mark Rosewater. (February 08, 2016.) "Are Event Decks and Clash Packs discontinued?", Blogatog, Tumblr.
- Blake Rasmussen. (December 18, 2017.) “Challenger Decks and the Final Duel Decks”, magicthegathering.com, Wizards of the Coast.