Dover (/ˈdoʊvər/ DOH-vər) is a town and major ferry port in Kent, southeast England. It faces France across the Strait of Dover, the narrowest part of the English Channel at 33 kilometres (21 mi) from Cap Gris Nez in France. It lies southeast of Canterbury and east of Maidstone. The town is the administrative centre of the Dover District and home of the Port of Dover.

Archaeological finds have revealed that the area has always been a focus for peoples entering and leaving Britain. The name derives from the River Dour that flows through it.

In recent times the town has undergone transformations with a high-speed rail link to London, new retail in town with St James' area opened in 2018, and a revamped promenade and beachfront. This followed in 2019, with a new 500m Pier to the west of the Harbour, and new Marina unveiled as part of a £330m investment in the area. It has also been a point of destination for many illegal migrant crossings.

The Port of Dover provides much of the town's employment, as does tourism including to the landmark White Cliffs of Dover. There were over 368,000 tourists visiting Dover castle in the year of 2019. Dover is classified as a Large-Port Town, due to its large volumes of port traffic and low urban population.

Archaeological finds have shown that there were Stone Age people in the area, and that some Iron Age finds also exist. During the Roman period, the area became part of the Roman communications network. It was connected by road to Canterbury and Watling Street and it became Portus Dubris, a fortified port. Dover has a partly preserved Roman lighthouse (the tallest surviving Roman structure in Britain) and the remains of a villa with preserved Roman wall paintings. Dover later figured in Domesday Book (1086).

Forts were built above the port and lighthouses were constructed to guide passing ships. It is one of the Cinque Ports. and has served as a bastion against various attackers: notably the French during the Napoleonic Wars and Germany during the Second World War.

During the Cold War, a regional seat of government was located within the White Cliffs beneath Dover Castle. This is omitted from the strategic objects appearing on the Soviet 1:10,000 city plan of Dover that was produced in 1974. The port would have served as an embarkation point for sending reinforcements to the British Army of the Rhine in the event of a Soviet ground invasion of Europe.

In 1974, a discovery was made at Langdon Bay off the coast near Dover. It contained bronze axes of French design and is probably the remainder of the cargo of a sunken ship. At the same time, this find also shows that trade routes across the Channel between England and France existed already in the Bronze Age, or even earlier. In 1992, the so-called Dover boat from the Bronze Age was discovered in six metres depth underwater. This is one of the oldest finds of a seaworthy boat. Using the radiocarbon method of investigation, the boat's construction was dated to approximately 1550 BC.