In general, the impacts of tourism vary according to the number and nature of tourists and the characteristics of the site. The individual tourist normally has a relatively small impact. Problems arise, however, if the number of tourists is large or the resource overused. Thus although tourism can be a lucrative source of revenue for a protected area, it can also represent a major management problem. As with most problems, the negative impacts of tourism can only be managed effectively if they have been identified, measured and evaluated. Once this has been done, tailored management responses can be created.