Almost every nation has a merchant marine, a fleet of ships which are usually owned and registered in that nation and fly under its flag, but are separate from the military. It carries goods and people, and is a vital part of the national economy. In addition, many countries use their merchant marine to supplement the military in times of war, with it transporting goods and equipment to areas where they are needed. For this reason, the merchant marine is sometimes called the merchant navy, indicating its dual role.
The people who staff the merchant marine are known as merchant marines, and while some have served in the military as well, most have chosen a career in the merchant navy. These people are usually well trained, dedicated men and women who have ranks and procedures just like members of the military do. Many have served during periods of war, and have been recognized and decorated for services to their home governments.
Those in the fleet have a system of ranks and specialties which closely correlates to that of the military. Some specialize in a particular field, such as navigation, communications, or heavy equipment operations. Others attend an academy to begin careers as officers. Most intend to remain in the merchant marine for the duration of their careers, and many companies provide benefits and incentives to encourage their staff to continue serving.
In general, to be considered a member of a nation's merchant marine, a ship must fly that nation's flag. Some ships may have foreign registration, but choose to fly under the flag of another nation for various reasons. The staff may be of mixed nationalities, although generally the officers represent the nation whose flag is flown.
Merchant marines also rely on an extensive ground network, which includes shipyards, truck and train systems, and ground staff who manage the company. When marine insurance companies, lawyers, research companies, and a variety of other industries related to marine are added, it represents a sizable portion of the economy, with ships being a crucial part of the transportation system.