Merchant ships in the context of "Natural harbour"

A harbor (American English), or harbour (Commonwealth English; see spelling differences), is a sheltered body of water where ships, boats, and barges can be moored. The term harbor is often used interchangeably with port, which is a man-made facility built for loading and unloading vessels and dropping off and picking up passengers. Harbors usually include one or more ports. Alexandria Port in Egypt, meanwhile, is an example of a port with two harbors.

Harbors may be natural or artificial. An artificial harbor can have deliberately constructed breakwaters, sea walls, or jetties or they can be constructed by dredging, which requires maintenance by further periodic dredging. An example of an artificial harbor is Long Beach Harbor, California, United States, which was an array of salt marshes and tidal flats too shallow for modern merchant ships before it was first dredged in the early 20th century. In contrast, a natural harbor is surrounded on several sides by land. Examples of natural harbors include Sydney Harbour, New South Wales, Australia, Halifax Harbour in Halifax, Nova Scotia, Canada, and Trincomalee Harbour in Sri Lanka.

The Regency of Algiers was an early modern semi-independent Ottoman province and nominal vassal state on the Barbary Coast of North Africa from 1516 to 1830. Founded by the privateer brothers Aruj and Hayreddin Reis (also known as the Barbarossa brothers), the Regency succeeded the Kingdom of Tlemcen as a formidable base that waged maritime holy war (Jihad) on European Christian powers. It was ruled by elected regents under a stratocracy led by Janissaries and corsairs. Despite its pirate reputation in Europe, Algiers maintained long-standing diplomatic ties with European states and was a recognized Mediterranean power.

The Regency emerged in the 16th-century Ottoman–Habsburg wars. As self-proclaimed ghazis gaining popular support and legitimacy from the religious leaders at the expense of hostile local emirs, the Barbarossa brothers and their successors carved a unique corsair state that drew revenue and political power from its naval warfare against Habsburg Spain. In the 17th century, when the wars between Spain and the Ottoman Empire, Kingdom of France, Kingdom of England and Dutch Republic ended, Barbary corsairs started capturing merchant ships and their crews and goods from these states. When the Ottomans could not prevent these attacks, European powers negotiated directly with Algiers and also took military action against it. This policy would emancipate Algiers from the Ottomans.

A warship or combatant ship is a naval ship that is used for naval warfare. Usually they belong to the navy branch of the armed forces of a nation, though they have also been operated by individuals, cooperatives and corporations. As well as being armed, warships are designed to withstand damage and are typically faster and more maneuverable than merchant ships. Unlike a merchant ship, which carries cargo, a warship typically carries only weapons, ammunition and supplies for its crew.

In wartime, the distinction between warships and merchant ships is often blurred. Until the 17th century it was common for merchant ships to be pressed into naval service, and not unusual for more than half of a fleet to be composed of merchant ships—there was not a large difference in construction, unlike the difference between a heavily armoured battleship and an ocean liner. Until the threat of piracy subsided in the 19th century, it was normal practice to arm larger merchant ships such as galleons. Warships have also often been used as troop carriers or supply ships, such as by the French Navy in the 18th century or the Imperial Japanese Navy during the Second World War. In war since the early 20th century, merchant ships were often armed and used as auxiliary warships, such as the Q-ships of the First World War and the armed merchant cruisers of the Second World War.

The International Convention for the Safety of Life at Sea (SOLAS) is an international maritime treaty which sets out minimum safety standards in the construction, equipment and operation of merchant ships. The International Maritime Organization convention requires signatory flag states to ensure that ships flagged by them comply with at least these standards.

Initially prompted by the sinking of the Titanic, the current version of SOLAS is the 1974 version, known as SOLAS 1974, which came into force on 25 May 1980, and has been amended several times. As of April 2022, SOLAS 1974 has 167 contracting states, which flag about 99% of merchant ships around the world in terms of gross tonnage.