National carriers are major airlines that operate scheduled flights within a specific country and often provide international services as well. They are typically owned or heavily regulated by the government and play a crucial role in connecting various regions, facilitating trade, and promoting tourism. Examples of national carriers include American Airlines in the United States and British Airways in the United Kingdom. These airlines often receive support from their governments, which can include financial assistance or favorable regulations. National carriers usually have a larger fleet and more extensive route networks compared to regional airlines, making them essential for both domestic and international travel.