A link is any HTML-anchor pointing to another site. It must be the
basic "a"-element as defined by the W3C , including the URL in the
"href"-attribute. The URL can be relative or absolute. Anything fancy
the like -- will be ignored. (Google also won't be able to spider the
pages linked to if it's the only link available online.)
So this is a link in terms of PageRank:
While this would not be:
This link must be on a public webpage (http- or https-something) which
Google spidered. The page should have the content-type "text/html".
Usenet newsgroup postings with a link won't directly help, though
indirectly because there are public web-archives making links out of
Now which links are important to increase the PageRank? It's the
non-spammy kind -- so thousands of guestbook backlinks won't help, but
a few links from high-quality pages with higher PRs than yours do
help. (Also, it's important to get links from the outside, versus just
getting links from your own domains.)
Note if the page linking to your page contains many, many links, then
we got what is called "link leakage" -- the importance of a link-value
decreases with the amount of links contained within the same page.
This is natural; imagine a great page only links to 3 other pages;
those must be really great (relevant, important, of high-quality),
too. However if it contains 200 links than probably the webmaster
didn't check those recently, or doesn't consider all of them as being
very important to the matter.
The easiest way to get those links to your page is really to create
great content people find interesting. And once in a while, to let
people know about it (e.g. via email).
To check your backlinks, you can enter "link:www.example.com" (no
quotes) in Google. You won't see all your backlinks, but a selection
-- mostly those of sites with a PageRank of 4 and higher.
Also, you can do the same at AllTheWeb:
For Blogs, the best backlink collector is:
An alternative: Daypop
To check the PageRank (PR) of your page or another page, download the
Google Toolbar and install with the advanced options (I suppose you
already know that):
Google Toolbar 2
Hope this helps!
 World Wide Web Consortium