Here are some terms and acronyms that you may encounter on various websites and forums.

SEO
Search Engine Optimization. This is the process of tuning your site and individual pages to improve the ranking of your site on a search engine query for a certain set of keywords. This can include changing the page itself, filenames, internal linking structures, titles, meta tags, and much more. This also includes off-page optimization such as incoming links, anchor text, directory submissions, etc.

SERP/SRP
Search Results page. This is the output pages of a search on a particular engine.

PageRank (PR)
This is the numeric popularity value Google gives a particular web page. Note that individual pages are given their own rank rather than entire sites. See the PageRank section for more details.

PPC (Pay-Per-Click)
This is a type of advertising in which a company pays a pre-determined amount every time someone clicks one of their ads. It is typically in the range of $.01 to $70. That is quite a range. This method is preferred by advertisers because they only pay when someone visits their site.

CPA (Cost per Action)
This is the cost incurred when a specific action takes place, such as clicking on a banner.

CPC (Cost per Click)
Cost per Click represents the amount an advertiser pays every time someone clicks one of their advertisements.

CPI (Cost per Impression)
In this advertising model ads are paid for being shown, not when clicked on. Sites showing the advertisements would generally prefer this method because they get paid whether the client’s ad performs well or not.

CPM
CPM stands for cost per thousand (the M is actually mille). You will often see it in relation to ad impression costs.

eCPA
Estimated Cost Per Action. If you are paying for ad impressions rather than clicks, this number will tell you how the impressions you paid for translated into cost per click.

eCPM
Estimated Cost per Thousand. For advertisers buying ad clicks, this will show how much it would’ve translated into if you were using a CPM (pay for impressions) model.

GoogleBot
This is the name of Google’s Web spider. If Google is spidering your site you will see GoogleBot in the user agent field in your web server’s logs.

Search Spider
This is the name given to the “robot” that a search engine sends to visit your site and collect data.