Blizzard has converted the StarCraft 2: Wings of Liberty demo into the StarCraft 2 Starter Edition.
The Starter Edition allows anyone to play selected content for free providing you have a Battle.net account and an internet connection.
Available are the first four missions of the StarCraft 2: Wings of Liberty single-player campaign, including Mar Sara 1-3 and the choice to embark on Tychuss first mission or Dr. Hansens first mission.
You also get the first two Challenges: Tactical Command and Covert Ops, access to the terran race in Custom Games and Single-Player vs. AI, and access to the following custom maps (map selection may rotate over time): XelNaga Caverns, Shattered Temple, Discord IV and High Orbit.
Any campaign progress and achievements you earn while playing StarCraft 2: Starter Edition are automatically saved to your Battle.net account, and carry over should you upgrade from the Starter Edition to the full version of StarCraft 2.