How to find and replace text using vi

How to find and replace text using vi or vim
Both vi and vim text editor comes with substitute command for finding and replacing text.
The syntax is as follows:
:%s/WORD-To-Find-HERE/Replace-Word-Here/g
OR
:%s/FindMe/ReplaceME/g
Examples
The substitute command can be used as per your requirements.
Task: VI / Vim Basic Find and Replace
To find each occurrence of ‘UNIX’, and replace it with ‘Linux’, enter (press ESC, type : and following command):
:%s/UNIX/Linux/g
Task: Find and Replace with Confirmation
Find a word called ‘UNIX’ and replace with ‘Linux’, but ask for confirmation first, enter:
:%s/UNIX/Linux/gc
Task: Find and Replace Whole Word Only
Find whole words exactly matching ‘UNIX’ to ‘Linux’; and ask for confirmation too:
:%s/\/Linux/gc