Highway is a term commonly used is to designate major roads intended for travel by the public between important destinations, such as cities. The term highway can also be varied country-to-country, and can be referred to a road, freeway, superhighway, autoroute, autobahn, parkway, expressway, autostrasse, autostrada, byway, auto-estrada or motorway.
Highway designs vary widely. They can include some characteristics of grade separations, multiple lanes of traffic, a median between lanes of opposing traffic, and access control (ramps and grade separation). Highways can also be as simple as a two-lane, shoulderless road.
The United States has the largest network of national highways, including Interstate highways and United States Numbered Highways. This network is present in every state and connects all major cities. China has the second largest highway system in the world.
According to world views, the characteristics of a highway can differ. For example, in the United States of America's state of California, civil code 360(590) defines that a highway refers to "any way or place of whatever nature, publicly maintained and open to the use of the public for purposes of vehicular travel." Streets, avenues and even one lane dirt roads are therefore considered highways within the state of California, so long as they are maintained by the state. Multi-lane, high-speed roadways with restricted access are called freeways according to California's civil code, whereby all freeways are highways but not all highways are freeways. In other jurisdictions, such as the Canadian province of Ontario, all public roadways are legally defined as a highway, regardless of its ownership.
Some highways, like the Pan-American Highway or the European routes, bridge multiple countries. Australia's Highway 1 is the longest national highway in the world at over 20,000km and runs almost the entire way around the country.
Highways are not always continuous stretches of pavement. For example, some highways are interrupted by bodies of water, and ferry routes may serve as sections of the highway.