The Webalizer is a fast web server log file analysis program. It produces highly detailed, easily configurable usage reports in HTML format, for viewing with a standard web browser.

Reports

By default, The Webalizer produces two kinds of reports - a yearly summary report and a detailed monthly report, one for each analyzed month.

The yearly summary report provides such information as the number of hits, file and page requests, hosts and visits, as well as daily averages of these counters for each month. The report is accompanied by a yearly summary graph.

Each of the monthly reports is generated as a single HTML page containing a monthly summary report (listing the overall number of hits, file and page requests, visits, hosts, etc), a daily report (grouping these counters for each of the days of the month), an aggregated hourly report (grouping counters for the same hour of each day together), a URL report (grouping collected information by URL), a host report (by IP address), website entry and exit URL reports (showing most common first and last visit URLs), a referrer report (grouping the referring third-party URLs leading to the analyzed website), a search string report (grouping items by search terms used in such search engines as Google), a user agent report (grouping by the browser type) and a country report (grouping by the host's country of origin).

Each of the standard HTML reports described above lists only top entries for each item (e.g. top 20 URLs). The actual number of lines for each of the reports is controlled by configuration. The Webalizer may also be configured to produce a separate report for each of the items, which will list every single item, such as all website visitors, all requested URLs, etc.

Overview

Website traffic analysis is produced by grouping and aggregating various data items captured by the web server in the form of log files while the website visitor is browsing the website. Some of the most commonly-used website traffic analysis terms are listed below:

• URL
  A Uniform Resource Locator (URL) uniquely identifies the resource requested by the user's browser.
• Hit
  Each HTTP request submitted by the browser is counted as one hit. Note that HTTP requests may be submitted for non-existent content, in which case they still will be counted. For example, if one of the five image files referred by the example page mentioned above is missing, the web server will still count six HTTP requests, but in this case, five will be marked as successful (one HTML file and four images) and one as a failed request (the missing image)
• Page
  A page is a successful HTTP request for a resource that constitutes primary website's content. Pages are usually identified by a file extension (e.g. .html, .php, .asp, etc) or by a missing extension, in which case the subject of the HTTP request is considered a directory and the default page for this directory is served.
• File
  Each successful HTTP request is counted as a file.
• Visitor
  A visitor is the actual person browsing the website. A typical website serves content to anonymous visitors and cannot associate visitors with the actual person browsing the website. Visitor identification may be based on their IP address or an HTTP cookie. The former approach is simple to implement, but results in all visitors browsing the same website from behind a firewall counted as a single visitor. The latter approach requires special configuration of the web server (i.e. to log HTTP cookies) and is more expensive to implement. Note that neither of the approaches identifies the actual person browsing the website and neither provides 100% accuracy in determining that the same visitor has visited the website again.
• Visit
  A visit is a series of HTTP requests submitted by a visitor with the maximum time between requests not exceeding a certain amount configured by the webmaster, which is typically set at 30 minutes. For example, if a visitor requested page A, then in 10 minutes page B and then in 40 minutes page C, then this visitor has generated two visits, one when pages A and B were requested and another when the page C was requested.
• Host
  In general, a host is the visitor's machine running the browser. Hosts are often identified by IP addresses or domain names. Those web traffic analysis tools that use IP addresses to identify visitors use the words hosts, domain names and IP addresses interchangeably.
• User Agent
  User agent is a synonym for a web browser.

In order to illustrate the difference between hits, pages and files, let's consider a user requesting an HTML file referring to five images, one of which is missing. In this case the web server will log six hits (i.e. one successful for the HTML file itself and four for successfully retrieved images and one for the missing image), five files (i.e. five successful HTML requests) and one page (i.e. the HTML file).