Remember that you can only go back and forward. If you go "Back" and then open a new page, you will loose your work as the Browser will not know where to go "Forward" to.
Think of it like a maze. If you go down a tunnel and write part of a message on the wall, you can use the "Back" and "Forward" buttons all day long to return to the entrance and "forward" to the message. Once you go "Back" to the entrance and start down a new tunnel, there is no "Forward" command to return you to the message.