Lets begin from examples:
1.You want to open online store. You have some items for sale but you need to extend assortment. You are going in the Web and are searching appropriate items to resale for commission. Then you need business partner.

2.Your site contains the great web promotion tools but you want to generate more traffic and you put in your page tools from other like sites (by agreement, of course). You have more traffic, your partner has free advertising.

3.Most ow well-known brands were created offline, and if you have no time to promote new brand you need co-branding.

Pay-Per-Click - You place on the server banner or link on another site, if someone will become interested and will click on link, to you for each click pay money. The sum oscillates from $ 0.01 up to $ 0.99.

Pay-Per-View - You place on the server banner on another site, and receive money for viewing of a banners. The sum oscillates from $0.20 up to $4 for 1000 views.

Pay-Per-Lead - Too most as Pay-Per-Click, but pay already for registration on a site for the sponsor. Here sums are more.

Pay-Per-Sale - If the visitor from your site purchases something on a site of the sponsor, to you there is a defined percent.

Pay-Per-Referral - If you attract another webmaster in advertising services of the sponsor, that the sponsor pays to you percent from the income new webmaster.

Pay-Per-Surf - If you like surf Internet and you are patient, it's for you.

Pay-Per-Read - some companies pay you for use their e-mail service (Trepass), or you read e-mail with ads (Amazing Solutions) and other. They have referral programs too.