> How to stop people to open my pages in a frame on their page?
It would be very difficult to detect, if not impossible. If you use
and if not, re-direct somewhere else or generate garbage.
> I noticed some people doing that with my pages. And I am trying to figure
> out how to stop them AND I try to figure out IF I should stop them...?
This depends on your site. If they put your on-line store catalogue in a
frame, would you mind? Do you have bandwidth restrictions? Are you being
referenced by sites that are not decent?
Google Images and Google Translations use this frame behaviour. Will you
want to stop them too?
> What are the pro's and cons for me if people do that.
Again, it depends on your interests and the nature of your site.
Roy S. Schestowitz