Measure inbound links
Most search engines like Google use inbound links or back links, depending on what you call them, to measure if a site is relevant for a specific search query made by an internet user. Even if inbound links are not all to get top of Google, they play a very big part in the process alongside other factors.
With inbound links, the quantity is not always important, but a lot of people only see the numbers instead of asking what is behind. There is absolutely no point in having thousands of links just naming your site. First, it is better to use anchor text links. This means that the link back to your site is on a word or phrase. So as a result, it is better to have fifty links to your site using one of your target keywords as a link rather than thousands of links simply using your URL as the link as it will make no difference on your ranking.
Going back to how we measure those links, there are various sites and software offering to do it for you. Strangely enough, you will find that the number of inbound links you have will vary depending on the site or software you use. As a result it is better to always use the same to look for an improvement or not.
You can also just go to the search engines page and ask them where your inbound links come from, as most search engines offer a method to measure them. While you would need to use the link:www.mydomain.com command on Google, Yahoo will requires linkdomain:www.mydomain.com. Unfortunately, MSN doesn’t tell you anymore the number of links you’ve got. It is important to note that using those commands on the search engines will not show you all your links. It is also important to know that Google will only show you a small sample of links, so do not get scared if you only see a few links. Yahoo is usually doing better and is in my opinion the best choice when it comes to looking at your inbound links. Using Google webmaster tool, you can also find out what some of your links are.
An SEO company will use those SEO tools regularly and will usually know a few. So if you ever use one for SEO services like link building, you can ask them about that. But remember that number is not all. Good links coming from relevant sites are the best.