Chernarus is a 225 km2 open world, devastated by an unknown infection that has wiped out most of its population, turning some of them into mindless zombies. That is where DayZ takes place. It's a fictional creation based on areas of the Czech Republic, where ArmA developer Bohemia Interactive is located.
The major features of Chernarus are three major cities: Chernogorsk, Elektrozavodsk, and Berezino; towns such as Stary Sobor and Zelenogorsk; airfields in the south, northwest, and northeast; great expanses of highly realistic forest; simply architectured and yet fabulous castles; masterfully created and voiced hordes of bloodthirsty zombies, and so much more.
Navigation of Chernarus can be time-consuming due to the massive size of the map. While running can take anywhere from 1-3 hours to cross the entire map, a vehicle can make this experience much more feasible. Driving off-road with a vehicle is sometimes required to reach certain locations or to cross stretches where roads are not present, however some form of road is usually available.
After obtaining a vehicle, there are different types of road which can be travelled on at different speeds and also deteriorate the wheels at different rates. The largest mainstream (orange) road in Chernarus stretches along the entire Southern coast and the majority of the Eastern coast. Travelling on this road will allow your vehicle to travel at full speed. You can also travel full speed on thinner roads (yellow) which still have the markings in the middle of the road.
Roads which are white are the most common in DayZ, and travelling at full speed is sometimes feasible depending on the location but it will not hinder your speed to a major degree. Travelling at full speed on an ATV or other fragile vehicle is not advised due to the abundance of sharp turns and hills which could prove a potential risk to the vehicle. Dirt tracks, shown as thin black lines and also dotted lines, will hinder your vehicle's speed notably (usually around half) but your speed will not be that of the off-road speed.