[hn_username]

Thanks for your reply. The ad-exchange-related jargon is foreign to me, but your explanation makes sense. Basically, the arbitrageur buys ad space on a website from a demand source (which essentially means buying a demand source tag which secures the ad space on that website) and turns around and re-sells that space which he/she just bought on a DSP. So, money is made when the cost to buy the ad space from the demand source is less than it's re-sold for on the DSP.

Is that about right? What information does the demand source tag include - is that basically a placeholder indicating you bought space for an ad on a website? I assume the arbitrageur's edge comes from finding traffic that can be bought cheaply from the demand source and sold higher on the DSP?

[very_difficult]

The information the demand source tag includes things such as domain name, ad size, among other things. Most of this information is publicly available--take a look at the AppNexus public wiki for more information.

This is generally something that only online ad professionals can pull off, but if you have enough of a bankroll, you can try it as well. It's a very saturated space and the amount of knowledge that goes into it is much more than what I'm able to include in a forum such as this. Good luck.