Webalizer is a very basic web stats program. It was one of the first available in the early days of mass hosting. Basically, because the application is "server side", you have access to it if your hosting company has it installed on their servers. The information is viewed through a browser window, and can be examined in either chart form or columns with numbers. Further, the information is stored and arranged in such a way as to facilitate integration into databases and spreadsheet control workbooks. The data includes customary items such as number of visitors by hour, day, month and year, referrers, browsers used, pages accessed, entry or exit pages, and keywords.
Typically, Webalizer is a free program and there are no restrictions on use in terms of number of domain names and number of page views. While it is considered an adequate program for webmasters who have nothing else to use, it does collect less information than other server side programs such as AwStats. It also exhibits limitations in distinguishing between unique and returning traffic. And, the application is not being expanded or developed like other more advanced programs, since the last version was upgraded in 2004.
Admittedly, the reports are very easy to read, and for the most part, each section is self-explanatory. For those individuals that do need help understanding the stats provided, hosts generally offer an explanation page, demo unit, or screen shots for customers to read. Like all tracked statistics, it requires some form of assumptions on the part of the webmaster or person analyzing the data, so hasty reactions to the stats should not be undertaken without verifying all factors. But, the information is sufficient enough to ascertain trends or patterns in user activity. Excellent opportunities can still be gleaned from Webalizer reports.
While this point is true of all statistics programs, because the interpretation of data is subjective, webmasters buying websites solely on the basis of these reports should request additional due diligence. If the purchase price is based only on what the seller interprets, and the asking amount is substantial, you are going to want more involved data or more substantiating statistics.
Webalizer was a great program in the beginning days of the web because it was freely provided by hosting companies. In those days, many hosts did not provide anything, so this program was a welcome addition to the monthly hosting package. It is still used by many companies, but now it competes with other statistics tracking applications. Some have the program installed on their servers and offer it along with other programs. Additionally, some clients still use the program to compare with other options that require placing pieces of code on individual websites.
Finally, the creator of the script that runs Webalizer has considerable documentation in terms of what each segment of the report means. He has included all limitations or reasons for information to be skewed, which is enormously helpful when interpreting the data. And, he is quite eager to hear about concerns or problems so that they can be fixed.