The overarching principle of Islamic finance is that all forms of interest are forbidden. The Islamic financial model works on the basis of risk sharing. The customer and the bank share the risk of any investment on agreed terms, and divide any profits between them. The main categories within Islamic finance are: Ijara, Ijara-wa-iqtina, Mudaraba, Murabaha and Musharaka. Ijara is a leasing agreement whereby the bank buys an item for a customer and then leases it back over a specific period. Ijara-wa-Iqtina is a similar arrangement, except that the customer is able to buy the item at the end of the contract. Mudaraba offers specialist investment by a financial expert in which the bank and the customer shares any profits. Customers risks losing their money if the investment is unsuccessful, although the bank will not charge a handling fee unless it turns a profit. Murabaha is a form of credit which enables customers to make a purchase without having to take out an interest bearing loan. The bank buys an item and then sells it on to the customer on a deferred basis. Musharaka is an investment partnership in which profit sharing terms are agreed in advance, and losses are pegged to the amount invested.