Most people will not know what you are talking about if you say cost per action. It sounds strange and really complex. If you shorten cost per action with cpa, most people will think that you are talking about income taxes.
Cost per action marketing is a form of affiliate marketing. Marketers join special networks that provide access to offers. These special offers allow for more ways to earn commissions than just straight sales. They might pay commissions for generating a lead or when a prospect enters an email address.
Businesses are looking at buying new leads. They need new customers and are always looking for cost effective ways to get more people into the business funnel. A cost per lead or cpa email submit can be attractive for an online marketer.
Think about a blog owner that is getting a lot of traffic. They might have a good readership that follows the blog and really likes the site. The blog owner might use multiple sources to bring traffic to the site. A social media page that posts updates of the latest blog posts might attract even more viewers.
Twitter is a popular social media site, but a marketer might have to use it differently when it comes to cost per action. You might have come across internet marketers that use twitter for cpa purposes. The marketer might be looking for the quick buck by doing this. They might post links on their twitter updates that send the social media user right to the offer.
The marketer should really consider the long term business opportunity of driving traffic with twitter. Instead of sending a social media prospect directly to an offer, they might want to get them to sign up for a mailing list. Driving social media traffic to a list gives a marketer multiple chances to build a relationship with the prospect. Driving cpa traffic directly to offers might be frowned upon by some cpa networks and could result in getting a cpa account banned.