Do-Follow Link: Is the ideal type of backlink for when a third party site creates a backlink and allows the bots to fully explore the content on teh 3rd party and as bots find the link the “link juice” is passed on to your site. This is the highest value link you can receive.
No-Follow Link: By comparison to a Do-follow link a 3rd party site may enter a “No-follow” code into the page where your link is located but it doesn’t mean you get no credit for the backlink. Google has in recent years clarified they are getting better at giving credit for no-follow if the site value is high.
CTR: Click-Thru-Rate: The rate at which clients will engage with your site once an ad unit or new organic ranking has been established. In the case of media buying or paid search it may also have many factors as to the quality of the ad funnel and whether or not a client clicked through to the end sale or lead gen activity.
CPL: Cost Per Lead. (With professional optimization and testing this should go down over 60 days and improve in quality)
CPM: Cost Per Mille: A pricing system set up to reflect Cost Per Thousand impressions.