VIM block comment

1. Go to the first line you want to comment, press Ctrl+V. This will put the editor in the VISUAL BLOCK mode.
2. Then using the arrow key and select until the last line.
3. Now press Shift+I, which will put the editor in INSERT mode and then press #. This will add a hash to the first line.
4. Then press Esc (give it a second), and it will insert a # character on all other selected lines.