How to use Diff Command in Linux

diff command compares two different files and reports the difference. The
output is very cryptic and not straight forward to read.

Syntax: diff [options] file1 file2

What was modified in my new file when compare to my old file?
The option -w in the diff command will ignore the white space while
performing the comparison.
In the following diff output:

o The lines above ---, indicates the changes happened in first file in the
 diff command (i.e name_list.txt).

o The lines below ---, indicates the changes happened to the second
 file in the diff command (i.e name_list_new.txt). The lines that
belong to the first file starts with < and the lines of second file starts
with >.

# diff -w name_list.txt name_list_new.txt

2c2,3
< John Doe
---
> John M Doe
> Jason Bourne