Check this if you're completely new to Internet Marketing
Experts, please feel free to chime in and add more.
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Newbie or Noob - A term to describe anyone new to an area, whether it be a particular forum online or the Internet.
Backlinks: Incoming links to a webpage
BTF: Below the Fold. Content that's below the viewable area of a browser.
Cloaking: Cloaking describes the technique of serving a different page to a search engine spider than what a human visitor sees.
CPA - Cost Per Action: A form of advertising where payment is dependent upon an action that a user performs such as making a purchase, signing up for a newsletter, or asking for a follow-up call.
CPC - Cost Per Click: A performance-based advertising model where the advertiser pays a set fee for every click on an ad.
CTR - Click Through Rate: Percentage of times a user responded to an advertisement by clicking on the ad button/banner.
IM: Internet Marketing (can also mean Instant Messaging)
OP: Original Poster. Refers to the person that started a new thread in a forum.
PLR: Private Label Rights. More info here: Private label rights - encyclopedia article about Private label rights.
PPC - Pay Per Click
SEM - Search Engine Marketing
SEO - Search Engine Optimization
SERP - Search Engine Results Page.