Passing through variable with out ruining the link

Being far from an "expert" I remember hearing that http://mysite.com will be read differently that http://mysite.com ... crap ... that would actually need to be http://mysite.com/index.php?source=socialmedia.

So is there a way to pass on a variable with out destroying the functionality of the link?

Thanks!

I wrote out a nice long reply, but BHW didn't like it so here's the condensed version.

I assume based on the sample querystring you gave that you want to do something like change your page based on where you are getting the traffic from. If this is the case and you are reasonably savvy with your scripting language of choice, look into the HTTP_REFERRER variable and how you can set things up to change depending on what page is referring to you.

If you want to send information around on your own site from page to page, sessions might be another solution - they're the same kind of thing used for shopping carts that keep track of what you're buying on eBay, etc.