An advertiser that is interested in posting banner ads on other sites has three basic options. The advertiser can:
These three arrangements take many forms and advertisers and publishers must choose the specific arrangement that best suits them. If you want to post banner ads on other sites but don't have the capital to mount a traditional advertising campaign, you may choose to exchange banner ads with other sites. There are two ways you can go about this. The first is to individually develop relationships with other Web sites and trade specific banners. This is a very natural process and allows you to place your banner ads conscientiously and post other Web site banner ads that fit your site well. Your banner ad doesn't end up on very many sites, however, unless you invest a whole lot of your time in seeking out interested webmasters.
If you want to get your banner ad on a lot of sites in a short amount of time (and don't want to pay for it) then your best bet is joining a banner exchange program.