SMS stands for Short Message Service, which is a text messaging service component of most telephone, internet, and mobile device systems. It is a way to send text-only messages of up to 160 characters between phones. SMS is the most widely used texting technology, despite the growing number of alternate ways to communicate. SMS is a stateless communication protocol in which every SMS message is considered entirely independent of other messages. It uses standardized communication protocols that let mobile devices exchange short text. SMS is used for M2M (Machine to Machine) communication, such as an LED display machine controlled by SMS, and some vehicle tracking companies use SMS for their data transport or telemetry needs. SMS is being increasingly challenged by Internet Protocol-based messaging services such as RCS, Apples iMessage, Signal, Facebook Messenger/WhatsApp, Telegram, Viber, WeChat (in China), and Line (in Japan), available on smartphones with internet connections.