Frank Watson from Search Engine Watch wrote a great article that contains some brief and simple definitions for some of the important terms for Tracking and Analytics. All are very important. Here are some that I wanted to point out:

Page Views: The number of pages viewed is the basis of analytics and site traffic. At best, page views are a rough measurement. They’re the building blocks of analytics. Click backs and refreshed pages get double counted, while partial page loads can be counted differently. They need to be factored in to make statistics accurate.

Unique Page Views: A filtered view based on the number of pages a visitor views without the duplication of double visits to various pages. Duplicated visits can be examined with another view for visitor pathing. Whether a unique should be defined as unique to a session or some other time frame is subject to interpretation.

Frequently Visited Pages: The popularity and number of pages can show what content brings in long tail traffic and other insightful facts.

Visitors: The start of all in-depth analytics. Visitors are customers and users of your services in whatever capacity they come in. Visitors can be associated with so many factors — but most importantly they’re the ones that take action. A standard of their measurement should be established. Without a cookie or information about the visitor’s IP address, the accuracy of this number varies greatly.

Unique Visitors: Similar to page views (separated by a time frame), a unique visitor is generally one who’s visited once during a day, week, or month. The length of time can be segmented by many analytics programs — exactly how is the issue.

Page Views Per Visit: This metric reflects the stickiness of a site — or would if measured the same way by all analytics programs. For sites that earn income from CPM ads, the sources of traffic that provide more inquisitive users is important. Tools should agree on how this element is measured.

Time Per Visit: This is self explanatory — and should be based on the length of the session.

Geographic Location: Technology allows programs to filter where a visitor has come from by using the IP address. This is another inaccurate system given shared IP addresses. AOL, for example, shares its IP address across many geographic locations. The good news: this is becoming more precise as time progresses.

Referring URL: Where traffic comes from — a search engine, an advertisement on a content site, a blog, or online forum — can send traffic your way. Referring URLs show whether a person used the organic or paid link on a SERP. They can also be used to find sites that send you traffic and to start developing relationships with those who like what you’re doing.

On Page Links Clicked: Some programs track what links a visitor clicks on your pages. By seeing what’s popular, you can add relevant content or new pages to improve the site’s traffic.

Anchor Text of Referring Links: Since we generally don’t control this one, the ability to know what terms your site is being referred by is important in advanced SEO  and general site development. Not all systems offer this feature, but it’s one to keep in mind.

Click Through Rate: The number of clicks divided by the number of impressions, or how many times an ad is served. This seems to be a standard definition.

Cost Per Acquisition: How this one is measured has a lot of ambiguity, not only to the analytics programs, but to Web site owners in general. Many times the thing being evaluated to provide the cost misses many actions that have value but aren’t specifically counted. With the ability to wipe cookies and many tracking programs overwriting where a visitor originates from, it’s hard at times to be specific or standard on this important measurement.

Much thanks to Frank Watson for spending the quality time to put all these definitions together.  All of these elements are important to look at with SEO. You really can’t just pick any of them out and just stick with a few. You need to have an understanding of all elements and work according to the results you are receiving.