National Trust, Britain's largest conservation organization, working for the preservation of places of historic interest and natural beauty in England, Wales, and Northern Ireland. The National Trust is a registered charity and is not government funded. It has over 3 million members. The National Trust for Scotland, which operates throughout Scotland, including the islands, is also a charity, though it is completely independent of the National Trust.

The National Trust was founded in 1895 to counter the threat to the countryside posed by industrialization and urban growth through direct ownership of the land and buildings. At that time it had 100 members. Today it is the largest private landowner in Britain, conserving over 248,000 hectares (612,000 acres) of countryside and almost 885 km (550 mi) of coast (which in turn support many rare species of birds, butterflies, and bats). It also looks after more than 200 gardens and many historic industrial buildings, including mills and mines, as well as farmhouses, inns, and a large part of several villages. Nearly all of its properties are inalienable, which means they cannot be sold or mortgaged. It is committed to the principle of public access to its property, which is not limited to its own members.

The National Trust is best known for the grand country houses that it opens to the public. Since 1937, Parliament has allowed such houses to pass into the ownership of the Trust free of tax and with endowments, and most of those it owns and cares for today are the result of this legislation.

The National Trust for Scotland has a membership of around a quarter of a million people, cares for over 40,450 hectares (100,000 acres) of land, and owns more than 100 properties.