A newsletter is a printed or electronic report containing news concerning the activities of a business or an organization that is sent to its members, customers, employees or other subscribers. Newsletters generally contain one main topic of interest to its recipients. A newsletter may be considered grey literature. E-newsletters are delivered electronically via e-mail and can be viewed as spamming if e-mail marketing is sent unsolicited.

The newsletter is the most common form of serial publication. About two-thirds of newsletters are internal publications, aimed towards employees and volunteers, while about one-third are external publications, aimed towards advocacy or special interest groups.