A form letter is a letter written from a template, rather than being specially composed for a specific recipient. The most general kind of form letter consists of one or more regions of boilerplate text interspersed with one or more substitution placeholders.

Although form letters are generally intended for a wide audience, many form letters include stylistic elements or features intended to appear specifically tailored to the recipient — for example, they might be signed by autopen and utilize features such as mail merge to automatically insert the names of individual recipients.

A letter created for printing and distribution to a group of people whose names and addresses are taken from a database and inserted by a mail merge program into a single basic document.

Form letters are often used as replies from people who get large amounts of correspondence, such as celebrities or politicians.

Other form letters are used to notify candidates as part of an application process, such as acceptance or rejection letters from publishing companies, colleges or prospective employers.