[looigi]

I don't think there is a universal definition. In my experience in concert promoting, it was basically a negotiated level of sponsorship. We'd say, if you want to be featured as "Sponsored by...", where we'll list your company as such on all posters, print, and broadcast ads, with type this big and in this color and positioned this way, etc... we want you to provide/do the following. They'd come back and say, how about we do X, Y and Z instead? We'd say it's a deal if you do X, Y and Q, they'd agree, it was formalized in the contract, and it was done.