Original: The series is made up of four core games: Warcraft: Orcs & Humans, Warcraft II: Tides of Darkness, Warcraft III: Reign of Chaos and its expansion pack, The Frozen Throne, and World of Warcraft.
Simplified: The different games from the series are Warcraft: Orcs and Humans, Warcraft 2: Battle.net edition (with an expansion pack) and Warcraft 3 and its expansion pack, The Frozen Throne.