Also known as an LOI, a letter of intent is usually a nonbinding written declaration by a party or parties to enter into a formal obligation, in good faith, based upon the primary deal terms that are summarized in the letter. Similar to a letter of agreement, the LOI may be signed by one party who intends, in good faith, to enter into a more formal obligation and which LOI may be used by the other party to make a public announcement of an impending deal.