Please note that there may be a small discrepancy between real time visitor data and the daily summary report available on the following day. Usually, the daily summary will show less unique visitors than the real time report because the real time report counts all visitors, including robots and other automated crawlers, while the daily report only includes visitors who used an actual web browser, and eliminates all others.

Warning: Enabling Hostname Lookups could decrease the loading speed of your website by as much as 35% because it forces the web server to do a Hostname Lookup for every visitor's IP address! Hostname Lookups should only be enabled if you absolutely need to see the countries and ISP's your visitors are connecting from in your Access Log file, and website statistics, and you are willing to accept the slower loading speed. When Hostname Lookups are disabled (by default), only visitors' IP numbers are shown, but not ISP hostnames or countries of origin (although a manual query can still be made to retrieve that information by clicking on the question mark next to each IP address on the report).

Pages:
The number of "pages" logged. Only files that don't match an entry in the NotPageList config parameter (and match an entry of OnlyFiles config parameter if used) are counted as "Pages". Usually pages are reserved for HTML files or CGI files, not images nor other files requested as a result of loading a "Page" (like js,css... files).

Hits:
Any files requested from the server (including files that are "Pages") except those that match the SkipFiles config parameter.

Bandwidth:
Total number of bytes for pages, images and files downloaded by web browsing.
Note 1: Of course, this number includes only traffic for web only (or mail only, or ftp only depending on value of LogType).
Note 2: This number does not include technical header data size used inside the HTTP or HTTPS protocol or by protocols at a lower level (TCP, IP...).
Because of two previous notes, this number is often lower than bandwith reported by your provider (your provider counts in most cases bandwitdh at a lower level and includes all IP and UDP traffic).

Entry Page:
First page viewed by a visitor during its visit.
Note: When a visit started at end of month to end at beginning of next month, you might have an Entry page for the month report and no Exit pages.
That's why Entry pages can be different than Exit pages.

Exit Page:
Last page viewed by a visitor during its visit.
Note: When a visit started at end of month to end at beginning of next month, you might have an Entry page for the month report and no Exit pages.
That's why Entry pages can be different than Exit pages.

Session Duration:
The time a visitor spent on your site for each visit.
Some Visits durations are 'unknown' because they can't always be calculated. This is the major reason for this:
- Visit was not finished when 'update' occurred.
- Visit started the last hour (after 23:00) of the last day of a month (A technical reason prevents  calculating duration of such sessions).

Grabber:
A browser that is used primarily for copying locally an entire site. These include for example "teleport", "webcapture", "webcopier"...

Direct access / Bookmark:
This number represent the number of hits or ratio of hits when a visit to your site comes from a direct access. This means the first page of your web site was called:
- By typing your URL on the web browser address bar
- By clicking on your URL stored by a visitor inside its favorites
- By clicking on your URL found everywhere but not another internet web pages (a link in a document, an application, etc...)
- Clicking an URL of your site inside a mail is often counted here.

Add To Favorites:
This value, available in the "miscellaneous chart", reports an estimated indicator that can be used to have an idea of the number of times a visitor has added your web site into its favorite bookmarks.
The technical rules for that is the following formula:
Number of Add to Favourites = round((x+y) / r)
where
x = Number of hits made by IE browsers for "/anydir/favicon.ico", with a referer field not defined, and with no 404 error code
y = Number of hits made by IE browsers for "/favicon.ico", with a referer field not defined, with or without 404 error code
r = Ratio of hits made by IE browsers compared to hits made by all browsers (r <= 1)

As you can see in formula, only IE is used to count reliable "add", the "Add to favourites" for other browsers are estimated using ratio of other browsers usage compared to ratio of IE usage. The reason is that only IE do a hit on favicon.ico nearly ONLY when a user add the page to its favourites. The other browsers make often hits on this file also for other reasons so we can't count one "hit" as one "add" since it might be a hit for another reason.
Hits are treated different from errors to avoid counting multiple hits made recursively in upper path when favicon.ico file is not found in deeper directory of path.
Note that this number is just an indicator that is in most case higher than true value. The reason is that even IE browser sometimes make hit on favicon without an "Add to favourites" action by a user.

HTTP Status Codes:
HTTP status codes are returned by web servers to indicate the status of a request. Codes 200 and 304 are used to tell the browser the page can be viewed. All other codes generates hits and traffic 'not seen' by the visitor. For example a return code 301 or 302 will tell the browser to ask another page. The browser will do another hit and should finaly receive the page with a return code 200 and 304. All codes that are 'unseen' traffic are isolated in the HTTP Status report chart, enabled by the directives ShowHTTPErrorsStats. in config file. You can also change value for 'not error' hits (set by default to 200 and 304 with the ValidHTTPcodes directive. The following table outlines all status codes defined for the HTTP/1.1 draft specification outlined in IETF rfc 2068.
They are 3-digit codes where the first digit of this code identifies the class of the status code and the remaining 2 digits correspond to the specific condition within the response class. They are classified in 5 categories:

• 1xx - informational
• 2xx - successful
• 3xx - redirection
• 4xx - client error 
• 5xx - server error 

SMTP Status Codes:
SMTP status codes are returned by mail servers to indicate the status of a sending/receiving mail. The status code depends on mail server and preprocessor used to analyze log file.
All codes that are failure codes are isolated in the SMTP Status report chart. You can decide which codes are successfull mail transfer that should not appear in this chart with the ValidSMTPCodes directive.
Here are values reported for most mail servers (This should also be values when mail log file is preprocessing with maillogconvert.pl).
SMTP Errors are classified in 3 categories:

• 2xx/3xx - successful
• 4xx - failure, asking sender to try later
• 5xx - permanent failure