Text messaging is a fun and innovative way to stay in touch by typing from your mobile device instead of placing a call. You can use your phone's keypad to send messages to other people on your network. You push "2" for "A" and push "2, 2" for "B", etc.  This service is normally offered by all major carriers at an additional monthly cost. 

Email service is a type of text messaging. Many carriers will offer an email account that is something like yournumber@carriername.com.  A wireless PDA or Smartphone also makes it possible for you to send and receive your personal email messages.  This service is also normally offered at an additional monthly cost and may work with only certain devices.