Summary
Unique visitors - How many different IP address's have visited your site, each IP counts as 1 unique visit, every other visit from this IP won't increase your unique visitors value. Unique visitors is also referred to as UVs.
Number of visits - How many times your visitors visit your site, so how many times they come and go from the IP. For example, if I were to visit your site for the first time, it'd count as 1 Unique visit and 1 Visit, however if I come back to your site 5 times more, it'll still be 1 unique visit but 5 visits.
Pages - How many different pages were visited, this is often a big number if you get a lot of visitors who reach different pages, such as on forums.
Hits - Absoloutely useless, counts everything. For instance each time a single image is displayed is a hit, I don't see any bonus in having the "Hits" counter.
Bandwidth - The amount of bandwidth used for the current month.
Monthly history
Displays the Summary (see above) of every previous month, including the current months stats, useful to see progression/downfall of your site's statistics each month, also provides totals/averages of every month that has statistics.
Days of month
Similar to the Monthly history (see above), however the Days of month category provides the Summary (see above) of each day's stats, including the current days stats, once again it's useful to see progression/downfall of your site's statistics each day of the month, also provides totals/averages of every day that has statistics.
Days of week
Similar to both the Monthly history and Days of month (see above), however the Days of week category provides the Summary (see above) of each day of the week's statistics, for example "Monday" had this many statistics "Tuesday" had this many and so on. Useful to determine what day your site is most busiest for competitions, important information etc.
Hours
Similar to the Monthly history, Days of month and Days of week (see above), however the Hours category provides the Summary (see above) of each hour of the day, once again it's useful to determine the busiest hours of your site.
Countries (Top 25)
The Countries (Top 25) category provides a list of 25 Countries who's users have visited your site based on the Summary (see above.) The list is in order; from the Country with the most visits to the least. You can hit the "Full list" link to view a full list of Countries which have visited your site. The Countries (Top 25) list is a very useful tool to determine where your main traffic is from.
Hosts (Top 25)
The Hosts (Top 25) has the same basic concept as the Countries (Top 25) (see above), instead it provides the information based on individual Hosts (often referred to as an IP or IP address), each IP address is referred to as "1 individual Host", this is where the Unique Visitors (see the Summary category above) comes from. Once again the list is in order; from the host that has visited your site the most to the least host that has visited your site. The Hosts (Top 25) list is once again; a very useful tool to determine which hosts (IPs) visit your site the most, if your site has a IP logging tool of some sort, you can see who the user is (for example on forums.) You can hit the "Full list" link to view a full list of Hosts which have visited your site.
Authenticated users (Top 10)
The Authenticated users (Top 10) category provides statistics based on the Summary (see above) it probably won't interest you for your site, however for some webmasters it's very useful. The Authenticated users (Top 10) category provides a list of "Authenticated" users (users who can enter password protected pages.) Other logins (and/or anonymous users) is basically all the other users who have accessed your site without authenticating themselves with a password. The Authenticated users tool is useful if you want to track which users login authenticating themselves. You can hit the "Full list" link to view a full list of Authenticated users which have visited your site.
Robots/Spiders visitors (Top 25)
The Robots/Spiders visitors (Top 25) category provides statistics based on the Summary (see above) including a new field called "Last visit" which is quite self explanatory, however as some people might not know what it means, it just shows the last visit of the bot. This tool is very useful to track which bots visit your site, when they visit your site and how many stats they do. You can hit the "Full list" link to view a full list of bots which have visited your site.
Visits duration
The Visits duration is based off the Summary (see above) and also introduces a new field called "Percent" which is quite self explainatory however for those of you who don't know, it just represents what percentage of that duration has been done, for example: 30 minutes could have a 99% which means 99% of your visitors stay on your site for 30 minutes. The Visits duration category is based on 8 durations, they are;
0s-30s
30s-2mn
2mn-5mn
5mn-15mn
15mn-30mn
30mn-1h
1h+
Unknown
All fairly self explanatory, the "Unknown" being more then 1h+. This tool also provides the Summary (see above) with the number of visits, it also provides the average duration that is spent on your site. This tool is once again very useful to track the time spent on your site via your users.
File type
The File type category is based on the Summary (see above) which also includes the "Percentage" field (see Visits duration above) basically this is another thing that probably won't interest you, and you'll probably find that it won't be useful at all. The File type category basically just counts the statistics for each file type viewed on your site, for example: an image extention such as .gif or a server file extension such as .php or .html. Although you might find that this tool is useless, it can be good to see which file types are using the most of your bandwidth, therefore you can either remove, re-size or whatever you like to it etc.
Pages-URL (Top 25)
The Pages-URL (Top 25) category has the URL of a page it uses it's own fields introducing 4 new fields to the table, and they are;
Viewed - How many times the URL is viewed.
Average size - Average size of the URL's loaded.
Entry - A page is counted as the "entry" page if it is the first page requested by a new visitor to the website (not a completely new visitor, but rather a new session.)
Exit - Similarly, a page is counted as an "exit" page if it is the last page the visitors views before leaving the website.
The Pages-URL (Top 25) category is quite useful if you want to see which pages are accessed the most, however if your link trails, for example: instead of just having viewtopic.php you have viewtopic.php?f=numbershere&t=numbershere then it will count that as "viewtopic.php" and not the actual url including the numbers, therefore it's not a reliable tool to use for tracking the certain stats of some URLs, for that I suggest Google Analytics. You can hit the "Full list" link to view a full list of URLs which have been accessed while your users have visited your site.
Browsers (Top 10)
The Browsers (Top 10) category is based on the Summary (see above), it also introduces 2 new fields, these include;
Browsers - The browser used to access your site, such as firefox, internet explorer, etc.
Grabber - A browser that is used primarily for copying locally an entire site.
This tool is useful to see which browsers get used the most on your site, which could help in making your site cross-referrence browser friendly, or if someone has an issue on one browser, you can see how many other people are using that browser and eventually get asking if everyone has the issue. You can hit the "Full list/Versions" link to view a full list of browsers which have been used to access your site.
Connect to site from
Connect to site from brings one new field;
Origin - The location in which the traffic came from, such as http://www.promotion-source.com for example.
This tool provides a very accurate reading of where your traffic comes from, meaning how they got to your site, it's split up into 3 difference sources they are;
1 - Direct address / Bookmark / Link in email.
2 - Links from an Internet Search Engine (google, yahoo etc.)
3 - Links from an external page (other web sites except search engines)
Unfortunately this tool doesn't provide a "Full list" option, therefore only shows 25 external links, the rest will be placed under "Unknown" however it's useful as it's in order, from the most hits to the least so you can always see that.
Search Keyphrases (Top 10)
The Search Keyphrases (Top 10) category introduces 2 new fields, they are;
Different keyphrases - What was searched in a search engine, which was clicked and directed the user to your site.
Search - How many searches were made on that particular keyword in a search engine that was clicked and brought to your site.
The Search Keyphrases (Top 10) tool is great as it provides a detailed list of the top 10 search phrases entered into a search engine that was clicked and directed the user to your site, which gives you an idea of what Keyphrases you should focus more on, and what Keyphrases you should focus less on. You can hit the "Full list" link to view a full list of Search Keyphrases which have been searched on an search engine and directed the user to your site.
Search Keywords (Top 25)
The Search Keywords (Top 25) category introduces only 1 new field, it is;
Different keywords - Similar to the "Different keyphrases" (see above) the Different keywords is based on separate keywords that were entered into a search engine, that was clicked and directed the user to your site.
The Search Keywords (Top 25) category is a great tool which gives you an idea of what keywords you should focus more on, and what keywords you should focus less on. You can hit the "Full list" link to view a full list of Keywords which have been searched on an search engine and directed the user to your site.
Miscellaneous
Not much to say about the Miscellaneous category, it just counts everything else, such as Browsers with Java support, Browsers with Macromedia Director Support, Javascript disabled, Hits on favicon.ico, etc. Only useful if your looking for that information, such as if your site need Javascript enabled, you can see how many people actually have it disabled etc.
HTTP Status codes
The HTTP Status codes category introduces 1 new field, it is;
HTTP Status codes which will probably be named as HTTP Status codes* - The name & numeric code of the HTTP redirect, example: 302 - Moved temporarily (redirect)
Displays the Summary (see above) of each HTTP Status page, example:
404 - Document Not Found
302 - Moved temporarily (redirect)
206 - Partial Content
301 - Moved permanently (redirect)
400 - Bad Request
403 - Forbidden
This tool is useful to see how many users of your site get each page, could benefit you to try and find exactly what page they get it on, so you can fix it as sometimes they can get annoying (mostly 404 errors.)
Well there you go, that's the whole Awstats program explained in a couple thousand words
Hope it helped you, just another way we're helping Promotion Source users find their way around the net
Note: I did write this whole thing from scratch, I would appreciate it if you didn't use this on your site without seeking my permission first, we'll sort something out
Thanks for the infomation about it though. 
