If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content


Merry Christmas
That was the first SMS message, sent in December 1992 from a software developer in the United Kingdom.
SMS was designed as a "short message service" between mobile phones. The messages needed to be short because mobile phone networks had constrained bandwidth at the time. A German engineer proposed the 160 character limit, justifying it based on the average length of postcard messages and telegrams. 1
An SMS from the early 2000s that uses "textspeak" to fit a longer message in less characters. Image source: Miss Puzzle
The 160 character limit still holds today, but now many mobile phones make it seem like there is no longer a limit by splitting long messages into multiple pieces and stitching them back together again.
SMS learned a few new tricks too: SMS messages can be sent to multiple recipients and include images. Still, compared to email, it's fairly limited in its functionality.
Despite its limitations, SMS is remarkably popular. In the early 2000s, SMS usage shot up in countries without reliable Internet service, since SMS travels over the cellular networks.
Now that many more countries do have high-speed wireless Internet, SMS is competing with messaging apps like WhatsApp and WeChat. Even so, it remains a common form of messaging since it works between any two phones on any network; no app download needed!
Just like email, SMS was originally intended for one-to-one communication, but it's now used as a way for governments and businesses to broadcast messages to many phones at once.
A government agency can send SMS messages to subscribed residents with alerts about missing persons, severe weather, and major road closures. 2,3
Alerts from the Berkeley Police Department and Alameda County
Similarly (though not quite as life-saving!), businesses can send SMS messages to customers to entice them with promotions. Mobile phone users are a captive audience; the average US smartphone user touches their phones more than 2,000 times a day and the average open rate for SMS messages is as high as 98%. 4,5
SMS marketing messages from local businesses.
🤔 What messaging app do you use? Do you prefer to communicate with friends by texting, calling, or some other medium? How has text-based communication changed your social interactions?
🙋🏽🙋🏻‍♀️🙋🏿‍♂️Do you have any questions about this topic? We'd love to answer—just ask in the questions area below!

Want to join the conversation?