Final answer:
E-mail is a form of online communication that involves sending and receiving text messages and documents over a computer network.
Step-by-step explanation:
The subject of your question is Computers and Technology. Specifically, it relates to the concept of e-mail. E-mail refers to text messages and documents that are transmitted over a computer network. It has become a very important means of communication in our digital age, allowing people to send and receive messages quickly and efficiently.