Vim: insert the same characters across multiple lines

Question

Sometimes I want to edit a certain visual block of text across multiple lines.

For example, I would take a text that looks like this:

name
comment
ph         


        

Answer 1

Use Ctrl+V to enter visual block mode
Move Up/Down to select the columns of text in the lines you want to comment.
Then hit Shift+i and type the text you want to insert.
Then hit Esc, wait 1 second and the inserted text will appear on every line