1. The Great Plains: This vast, flat region covers much of northern and western Texas. It's characterized by rolling hills, grasslands, and occasional mesas.

2. The Edwards Plateau: This elevated plateau in central Texas is known for its rugged canyons, limestone hills, and unique vegetation.

3. The Gulf Coastal Plain: This lowland region stretches along the Texas coast and is characterized by flat, fertile land, swamps, and barrier islands.