How to switch from one directory to other directory in Linux or Unix operating system

 In Linux and Unix there is one program or command called "cd" which stand for change directory.

we can compare this cd with windows double click.

Example :-  

cd /opt/ABC/

/opt/ABC is the path where user want to enter.

or user can go first /opt then go to ABC

cd /opt  press enter

cd ABC press enter.