Send a message showing the meaning of blue in "Delivered".

Blue means that you are all connected to the Internet and all use Apple phones.

When texting with iPhone, you may find that your messages have two colors: green and blue background. When sending information with a blue background, certain conditions are required. First, you must use Apple iPhone to open the iMessage function service in Settings-Information.

Information refers to the objects transmitted and processed through audio, news and communication systems, and generally refers to all the contents spread by human society. People can distinguish different things by obtaining and identifying different information from nature and society, so as to understand and transform the world. In all communication and control systems, information is a common form of communication.