"Letters of Intent, legally, are the worst of all worlds. Writing a letter of intent is not to be taken lightly. In law, you either have a contract or you don't. LOI's are the legal equivalent of "almost pregnant." Letters of Intent emphatically state that. They state that they are not formal agreements, and then often proceed to set forth agreed terms of the proposed transaction. Given this paradox, if the deal goes sour, one party can argue [in court] that those agreed_upon points were, in fact, agreed upon _ or, in fact, a binding contract. And, in some cases, furthermore, that the party relied on the LOI and has monetary damages based on such reliance."
There are various types of letters of intents for instance if you are applying for university or college then you would need to create a letter of intent for graduate school or university. If you are planning to apply for a job then you would need a letter of intent for a particular job position.