Regional airlines are smaller carriers that operate flights within a specific area, often connecting smaller cities to larger hubs. They typically serve routes that are not profitable for major airlines, providing essential air travel options for passengers in less populated regions. These airlines often use smaller aircraft, which allows them to operate in airports with shorter runways. Regional airlines may operate independently or as partners with larger airlines, often under codeshare agreements, which helps expand the network of both types of carriers. Examples of regional airlines include SkyWest Airlines and Piedmont Airlines.