You'll be able to try Blizzard's long-awaited new game Diablo 3 without having to buy it.
This will be done via a Starter Edition of the game downloadable from Battle.net. For the first 30 days after Diablo 3's launch (tomorrow), the Starter Edition will only be accessible with a Guest Pass. These Guest Pass keys are contained within all boxed copies of Diablo 3.
The Starter Edition contains roughly the same content as the beta. You can play Act 1 up to the Skeleton King, and up to a character level of 13. You can only use the Matchmaking feature with other Starter Edition players, and you won't be able to use the Real Money Auction House.
Blizzard has also announced the impending launch of Diablo 3 Character Profiles on the game's official website. These track and present your Diablo 3 progress. You'll be able to see your heroes and their equipment and skills, and you'll be able to monitor all your progress at a glance.
There are plans to later add tabs to show your artisans (tradespeople you can level up) and achievements.