Text messaging, or texting is the common term for the sending of "short" (160 characters or fewer) text messages, using the Short Message Service, from mobile phones. It is available on most digital mobile phones and some personal digital assistants with onboard wireless telecommunications. The individual messages which are sent are called text messages, and more colloquially SMSes, texts, or even txts (in "text speak").
SMS gateways exist to connect mobile SMS services with instant message (IM) services, the world wide web, desktop computers, and even landline telephones (through speech synthesis). Devices which can connect to mobile phones and PDAs through protocols such as Bluetooth can also sometimes use that link to send SMS messages over the wireless network. SMS arose as part of the widely deployed GSM protocol, but is now also available with non-GSM systems.
The most common application of the service is person-to-person messaging, but text messages are also often used to interact with automated systems, such as ordering products and services for mobile phones, or participating in contests. There are some services available on the Internet that allow users to send text messages free of direct charge to the sender, although users of North American networks will often have to pay to receive any SMS text message
