The only reason to use this tool is to know if you're progressing in your SEO.

This tool uses Yahoo, therefore it will tell you how many backlinks you have on Yahoo. Google does not reveal the real number of backlinks - that's why this tool uses Yahoo.

It's not suggested you use such tools often - because if you're following link building techniques that are proven then your backlinks should increase as well as your pagerank.

If you have been getting links for the past 3 months but you only have 200 backlinks - something is wrong - but in general you should see the number growing. Again don't rely on progress a lot of tools like these.

To check out your progress it's quite simple. If you rankings are improving with time or not is the best indicator of progress!

Finally a Google Webmaster Tools account will reveal more detail about your backlinks and so on. It's worth it taking a look just so you know the numbers and detail. To look around, see and get a feel of how it's going on with your website and search engines.