A lease is a legal agreement between the landlord (the freeholder) and the person buying the lease (the leaseholder). It gives the leaseholder rights over the property for a fixed term of years. For Right to buy leases this is usually 125 years.
Buying a long lease on a property gives you the right to live in that property for the number of years that are remaining on the lease. During that time you are able to sell the lease of the property to another person/company. The lease sets out the obligations of both the leaseholder and the freeholder.
In some cases therefore, in documents and legislation you may find that you are referred to as a ‘tenant’. At the end of the lease, the property will once again return to the freeholder. In most cases you can apply to have the lease extended and in some circumstances apply to buy the freehold.