Mark all forums as read
This is used to mark all forums as read when you are browsing the forum and decide that there are no more 'old posts' that you want to read. This is done by making a cookie that contains the current time and date and using that to decide if the posts are old or not. Otherwise the last login date is used to indicate this.
Delete forum marking cookie
If you need to remove the cookie then this link is used to do that.