- Add a string (comment for example) at the beginning of several lines:
     * Use Ctrl+V to select the first column of text in the lines you want to comment. (using up/down arrows to highlight the portion needed)
     * 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.
  - Add a string at the end: <code>:%s/$/string you want to add at the end/g</code>