A messaging app may refer to popular instant messaging apps such as WhatsApp, Telegram or Facebook Messenger, or to the built-in SMS/MMS texting app in every phone. SMS does not require an internet connection, making it easy for users to find their messages. The simplest way to set up an SMS ordering system is to ask customers to text in a keyword to receive an automated message with a link to order online (a keyword is a word, phrase, or other combination of numbers and letters that allows people to receive an SMS from you).