Going direct with a large website where an I/O is needed.
What does it mean when they want me to send them a "tag?"
Never heard of this wording before, is this my usual tracking link? From like cpvlab/imobitrax or whatever?
it's an Ad tag you get from your ad server, depending on what you use it'll be some javascript or some html like an iframe.
It'll just contain a link that'll call the creatives from your ad server.
The website that you're doing a buy with needs to be able to serve the banner impressions with your ad tag.
If you have an ad server like adshuffle.com, you can grab that tag and send it to the website. Your ad tag will rotate your banners based on the weights that you provide for each creative.
If you don't have an ad server, you can ask if they can serve the banners from their server. Usually bigger sites will have an ad server in place.
The disadvantage of not using an ad server is not being able to add creatives or pause creatives right away.