Having a website, doing on-page and off-page optimization and analyzing visitors is not everything what webmasters and internet marketers should do. You need to know how your website is ranking in various search engines (at least Google, Yahoo and Bing). This applies for every keyword you are interested in. Knowing the search engine result page (SERP) position is important to understand the traffic volume, any fluctuations in income or just any other parameter that might be related to search engine ranking.
In general you can track few keywords manually. You can simple enter that phrase in browser and check position of your target page. But the manual approach lacks many important steps. It is not enough to check ranking, it is almost mandatory to record positions and other relevant data.
Having a history of positions can help you to determine what changes to the website have contributed to some significant change in ranking. Of course, fluctuations in positions are natural, search engine algorithms change, new websites come every day and many factors contribute to the position of your website in search results.
The best way to track ranking is to use some software. There any many such tools around. Market Samurai, for example, has an excellent rank tracker module. It tracks not only rank positions but also the number of backlinks and PageRank.
You only need to periodically trigger updates and all relevant data will be collected and stored into database. At any time you can get the latest data and you can also display graphs showing progress over time.
How you can use the tracking data? You can track the progress of each target keyword. If you are doing SEO you will monitor the effect of each change in page content or external links. The effects are not immediately seen, but sooner or later you should spot the difference.
If the change in ranking drops significantly then this might be a signal of some wrong action on the website. You should not mix initial ranking fluctuations that are very common for new websites with ranking changes of older and established pages.
Anyway, rank tracker is one of the tools in trade. If internet marketing is your business then you are probably using it on a daily basis. Remember, position in search engine results in not only SEO, it is also a reflection of the quality and usefulness of the content. Quality baclinks significantly contribute to higher ranking, getting them is pretty easy with good content.