Which of the following option is not used for communication within network ?

TCP/IP
HTML
HTTP
SMTP

The correct answer is (b), HTML. HTML is a markup language used to create web pages. It is not used for communication within a network.

TCP/IP is a protocol suite that is used to connect computers to the internet. It is used to break down data into smaller packets that can be sent over the network.

HTTP is a protocol that is used to transfer data between a web server and a web browser. It is used to request and receive web pages.

SMTP is a protocol that is used to send email. It is used to send email messages from one computer to another.