Online ads
CPC：Cost Per Click, for example: adsense *
CPM：Cost per mille (CPM), also called cost ‰ and cost per thousand (CPT)
CPA：Cost Per Action，Cost per action (CPA) affiliate programs encompass both pay per sale and pay per lead affiliate programs. Pay per sale affiliate programs pay you either a fixed amount per sale or a percentage of every sale generated from your links. Pay per lead affiliate programs generally pay for lead information (name, e-mail, phone, etc.) generated from your affiliate links. 也可以理解为付费试用的那种低价销售，介于CPL和CPS之间。
CPL：Cost Per Lead，即完全免费的sign up，以收集潜在客户资料为目的的广告形式。
CPS：Cost Per Sale，按实际销售产品金额或数量来换算广告费, affiliate program *
CTR：click-thru rate. 原本的定义为：点击与显示之比；用在CPL上面则也可以称之为：注册与显示之比。
