Original: The Wario Land series is a platforming series that started with Wario Land: Super Mario Land 3, a spin-off of the Super Mario Land series, following Wario's first appearance in Super Mario Land 2: 6 Golden Coins.
Simplified: The Wario series is a series of games that star Wario. It started out with Wario Land: Super Mario Land 3, and has grown to have its new spin-off series with WarioWare, Inc.: Mega Microgame $!.