A train operating company (TOC) is a business operating passenger trains on the railway system of Great Britain under the collective National Rail brand. TOCs have existed since the privatisation of the network under the Railways Act 1993. There are two types of TOC: most hold franchises let by the government, following bids from various companies, to operate services on certain routes for a specified duration, while a small number of “open-access” operators hold licences to provide supplementary services on chosen routes. These operators can run services for the duration of the licence validity. The franchised operators have changed considerably since privatisation: previous franchises have been divided, merged, re-let to new operators, or renamed. The term is also sometimes used to describe companies operating passenger or freight rail services over tracks that are owned by another company or a national network owner.