Gravel bike/ CX

Gravel bike is a combination of a road bike and a cyclo-cross bike. Mellow single tracks, farm roads, gravel, crushed cobblestones, tarmac — whatever. It's a machine that's capable of performing on various surfaces while sustaining comfort.
A cyclo-cross bicycle is a bicycle specifically designed for the rigors of a cyclo-cross (CX) race with max of 33 mm tire with (according to UCI standards).