A typical project is underpinned by a complex web of contractual relationships between the parties involved in the project, eg the project company, equity investors, contractors, sub-contractors, off-takers and suppliers (see Practice Note: Project finance—key project parties). The documents governing these relationships are generally referred to as the 'project documents'. For more information on project documents generally, see: Project documents: issues for lenders—overview. In many projects, a concession contract is one of the principal project documents. A concession contract governs the relationship between the host government (or governmental authority) and the project company. What are 'concessions' in the context of project finance transactions? Many projects involve some sort of collaboration between the private sector and the public sector. Depending on the structure of the project, the private sector may take responsibility for scoping, designing, financing, constructing and/or operating a project. Often, though, the government in the country where the project is located (the 'host government') will also have to, or want to, be involved in the project to some extent. Typically,