So I was on a forum today and there was a discussion going on about what are the different types of links. The only thing that was evident was that no one on the forum knew what they were talking about. So I typed up this response. Let me know what you think!
Lets do a little analogy. A link is like a baby.. when its born they are all equal... they all have the same potential. But as they start to grow up things start to change.
Some live in a bad neighborhood (link farm or link exchange) so their potential for growing up and becoming successful diminishes. Others move to a good neighborhood but end up a C Student so they just blend in with everyone else (links on a PR0 or PR1 blog, article site, directory listing. All of these links live in the average world so they have little impact on society (your site).
Now others take time to stand out and not to blend in (non duplicate content on authority sites (PR2, PR3, & PR4). These links are like college graduates which have doubled their lifetime earning potential. It took them a little longer but their value sticks around and can even grow in time.
Then there are those that invest heavy in an graduate school (PR5, PR6) they realize that no matter how hard they work they aren't going to get everything out of life that they want unless they spend a little money. So they invest (in their education) and their value grows exponentially.
Lastly, their are those super smart super rich kids that get their MBA from Wharton and go on to start billion dollar firms (PR7+). There are very few of them and they are very sought after by the younger links (your site is a PR0 so why would they link to you?).
All links are not the same. Neither are the sources you get them from. The more a site links out the less value it has. The more duplicate content on a site the less value it has.
Did you know a single PR9 link to your site is worth 98,000 PR1 links? Think about that for a second. If you can get a PR9 to link to you for a specific keyword (based on the level of competition) you will be considered one of the top sources for info on that relative topic. How much would you be willing to pay for that? Well I'd pay a fortune... guess what... none are for sale.
Link building has become a science over the last few years.. all the art is gone. Becareful where your links come from... the smarter the link the more value it creates..
If you have any questions about link building please let me know!