A familygram is a personal message sent to a sailor of the United States Navy on a submarine by their families. Because submarines normally maintain radio silence to avoid detection, personal messages from the 'outside world' are severely restricted. Familygrams were originally limited to 15 words, though later as many as 50 words or more were permitted. There are many examples of such familygrams on the Internet, dating from the Vietnam War and earlier. The term is also used colloquially by families wishing to communicate news to friends and extended family via printed or email newsletters.