If the letter of intent is accepted, then the due diligence period will begin. It will continue until the time agreed upon by both parties in which, at the end of the term, a binding contract is constructed. Terms may change during this time if certain aspects of a property, previously not disclosed, are discovered.
In the business world letters of intent are often used to prove to potential investors that a potential deal or merger may take place. Without such proof, investors may not be so willing to loan out the much needed money. While letters of intent are common in the business world there are also other instances where letters of intent are used.