Northumberland (RP pronunciation /nɔːˈθʌmbələnd/local /nɔːˈθʊmbələnd/) (abbreviated Northd) is a county in North East England. The northernmost county of England, it borders Cumbria to the west, County Durham and Tyne and Wear to the south and Scotland to the north. To the east is the North Sea coastline with a 64-mile (103 km) long distance path. The county town is Alnwick although the county council is in Morpeth (for the moment, as there are plans to move it to nearby Ashington). The northernmost point of Northumberland and England is at Marshall Meadows Bay.

The county of Northumberland included Newcastle upon Tyne until 1400, when the city became a county of itself. Northumberland expanded greatly in the Tudor period, annexing Berwick-upon-Tweed in 1482, Tynedale in 1495, Tynemouth in 1536, Redesdale around 1542 and Hexhamshire in 1572.Islandshire, Bedlingtonshire and Norhamshire were incorporated into Northumberland in 1844.Tynemouth and other settlements in North Tyneside were transferred to Tyne and Wear in 1974 under the Local Government Act 1972.