What is a .vimrc file and what should be its location? How to replace tab with 4 spaces using .vimrc?

Question

I have a large file which has "some string"so many times, i want it to be replaced with "other string" at all places, using vi or vim editor?
Is there any way to do that?

Answer 1

.vimrc is vim configuration file.
Here you can:
1. set whether to show numbers in file or not
2. set whether searching should be highlighted etc

It's location by default is
/home/user_name/.vimrc
set shiftwidth=4
set tabstop=4
set expandtab