Below you can see a list of technical terms used throughout this site and their intended meaning (which may well differ from what you have heard before).

1. ACRank
2. ACRank spread
3. Short domain
4. Long domain
5. Page vs Link
6. Reported vs Total
7. Referring domain
8. Source Flags
9. Mentions

1. ACRank

   ACRank stands for A-Citation-Rank. It is a very simple measure of how important a particular page is by assigning an integer value from 0 (lowest) to 15 (highest) depending on number of unique referring external short domains. Therefore in order for a page or link to have ACRank of 1 or higher it needs to have at least one external backlink. Below you can see ACRank distribution table showing minimum number of domains for each ACRank level:

   Rank	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15
   Ref Domains	0	1	1	2	4	8	16	32	128	256	1,024	2,048	8,192	16,384	65,536	131,072

   ACRank is a very simple and primitive measure of importance that allows to prioritise analysis by looking at data with the highest ACRanks first, however it should be said that in it's current design it suffers from a serious drawback: actual ACRank weight of backlink is not taken into account, so a page with one backlink of ACRank 1 will have the same ACRank value of 1 just like the other page that has got backlink with ACRank of 10 (or 15), clearly the latter page should have gotten higher ACRank as being linked to from the more important pages intuitively makes the page they linked too also more important. This drawback is going to be addressed shortly, despite their existance ACRank makes it easier to analyse data that is likely to have the highest weight. Meanwhile a concept of ACRank spread is used in attempt to have better comparison of pages that might have the same ACRank. Thresholds shown above can be expected to change in April 2008 when a new big index update is planned to happen.

   You may notice that 1 domain is specified for rank 1 and 2 - this is because Rank 1 will be given only if there is a single external backlink, where as Rank 2 will be given if there is more than one external link but they all come from single external domain. This is done to split off some of the more valuable Rank 1 pages that would otherwise be mixed up together.

2. ACRank spread

   ACRank spread shows number of ACRanked backlinks split by their ACRank, ie:

   Rank	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15
   Backlinks	1,024	512	256	128	64	32	16	8	4	2	-	-	-	-	-	-

   The table above shows fairly typical distribution (for a high ACRanked page) - normally the higher ACRank the less such backlinks exist, in some cases there gaps for lower value ACRank, sometimes there are none. The purpose of ACRank spread is to show diversity of backlink ACRanks and thus estimate value of the URL they point to better, or maybe drill down to see actual backlinks.

3. Short Domain

   Short domain (also sometimes referred to as second level domain) is the shortest form of the domain without any subdomains, ie: example.com. In cases of established multi-word TLDs, such as ".co.uk" short domain will be example.co.uk, this is applied to other TLDs as well and when 2nd level word is org/net/com as well as a few others. So, in general, short domain is the shortest possible form of domain without any subdomains.

4. Long Domain

   Long domain is a short domain with subdomain, ie: www.example.com or ftp.example.com, both of these are long domains of the short domain example.com.

5. Page vs Link

   In context of pages vs links, "page" refers to a URL that was actually crawled successfully and included into the index. Backlinks are always referring pages because we could not know what they link to if they were not crawled successfully.

   "Link" refers to URLs that were found to be referenced from one or more of the crawled pages, but the link itself has not been crawled yet (or the crawl was attempted but it failed for one of the many reasons).

6. Reported vs Total

   Some domains (many in fact) have got millions of backlinks, so domain analysis process has to make a decision which ones will be extracted to be shown in the final reports and which ones left behind: the decision which ones to take is based on ACRank of the urls and backlinks, so that the highest of them will get the best chance to make it into final reports. However it is always important to "know the unknown", which is the information on what other data is also present, but not shown in report - this amount is referred to as "total". So, "reported" is what you can drill down in reports to see, where as "total" can be the same or higher than reported, either way you will know how big it is.

7. Ref Domain

   Ref domain is a "referring domain", a domain from which backlink is pointing to a page or link.

8. Source flags

   Source flags are designed to differentiate between different types of backlinks. The following source flags are currently in use:

   Source Flag	Description
   Redirect	Set if source backlink redirected (using HTTP response codes 301, 302 or META Refresh based redirect) to target location
   Frame	Set if backlink was used in FRAME/IFRAME tags
   NoFollow	Set if backlink was marked as nofollow either via META tag or rel="nofollow"
   Images	Set if backlink was an image
   Deleted (or OldCrawl)	Set if upon recrawl of that page it was established that the backlink found there in previous crawls was deleted. This often happens when backlink from homepage goes into one of the deeper pages as new items take real estate on that page.
   AltText	Two cases: 1. If anchor text is present: it was taken from alt/title attributes of an A tag. 2. If anchor text is NOT present: target URL was found in normal text on the page - in essense it was mentioned there. Such mentions can present a good link building opportunity.

   Using Analysis Options it is possible to exclude/include backlinks with specific source flags.

9. Mentions

   Mentions are references to domain names or urls that we find in plain text, this is only done for domains other than the one referred to.