Dirt road is a common term for an unpaved road made from the native material of the land surface through which it passes, known to highway engineers as subgrade material. Dirt roads are suitable for vehicles; a narrower path for pedestrians, animals, and possibly small vehicles would be called a dirt track—the distinction is not well-defined. Unpaved roads with a harder surface made by the addition of material such as gravel and aggregate (stones), might be referred to as dirt roads in common usage but are distinguished as improved roads by highway engineers. (Improved unpaved roads include gravel roads, laterite roads, murram roads and macadamized roads).

Compared to a gravel road, a dirt road is not usually graded regularly to produce an enhanced camber to encourage rainwater to drain off the road, and drainage ditches at the sides may be absent. They are unlikely to have embankments through low-lying areas. This leads to greater waterlogging and erosion, and after heavy rain the road may be impassable even to off-road vehicles. For this reason, in some countries, such as Australia and New Zealand, they are known as dry-weather roads.

Dirt is unclean matter, especially when in contact with a person's clothes, skin or possessions when they are said to become dirty. Common types of dirt include:

When things are dirty they are usually cleaned with solutions like hard surface cleaner and other chemicals; much domestic activity is for this purpose — washing, sweeping and so forth.

In a commercial setting, a dirty appearance will give a bad impression of a place such as a restaurant. The dirt in such cases may be classified as temporary, permanent and deliberate. Temporary dirt is streaks and detritus that may be removed by ordinary daily cleaning. Permanent dirt is ingrained stains or physical damage which require major renovation to remove. Deliberate dirt is that which results from design decisions such as decor in dirty yellow or grunge styling.

As cities developed, arrangements were made for the disposal of dirt. In Britain, the Public Health Act 1875 required households to place their refuse into a container which could be moved so that it could be carted away. This was the first legal creation of the dustbin.

A road is a route, thoroughfare or way that supports travel by a means of conveyance.

For purposes of international statistical comparison, the Organisation for Economic Co-operation and Development (OECD) defines a road as "a line of communication (travelled way) using a stabilized base other than rails or air strips open to public traffic, primarily for the use of road motor vehicles running on their own wheels," which includes "bridges, tunnels, supporting structures, junctions, crossings, interchanges, and toll roads, but not cycle paths." In urban areas roads may diverge through a city or village and be named as streets, serving a dual function as urban space easement and route. Modern roads are normally smoothed, paved, or otherwise prepared to allow easy travel. Historically many roads were simply recognizable routes without any formal construction or maintenance.

In the United States, laws distinguish between public roads, which are open to public use, and private roads, which are privately controlled.