There are two goals for link building search engine optimization
. They are to enhance traffic to the site and also to improve the sites position in the search engines. A sites position will improve with the number of backlinks that it has. Having said that, in this instance the quality of the links is a lot more important than quantity. Getting lots of low quality backlinks is nowhere near as valuable as obtaining two good quality links. Search engines like Google and many others will give a website a high rank if it has a number of quality backlinks since they look at the site as important. There are some things to identify the value of a backlink and they're listed below.
1) Anchor text. Basically, anchor text is the text that is visible to a person looking at the link. For instance, clicking on a link to a car insurance company like Progressive might take you to progressive.com, but the text you see and click on might read "auto insurance". Anchor text that's descriptive about the website or web page offers greater value than a simple URL link in terms of link building SEO.
2: Page authority. Placing your links on websites or web pages that have greater value in the eyes of the search engines is important. Links from .gov sites are generally much more beneficial than obtaining links from a .com site which has not real authority.
3 Number of links on the web page. You will get more value for your link if you're the only link on the webpage where you put the link. You can see it in mathematical terms. On a page that has a value of 100 if you are the only link you're going to acquire 100% of the value however if your link is there with 20 other links then you'll only receive 5% value.
4: Domain age. The age of the domain where the backlink is placed provides some value on the link. This is because older and more established sites are more trusted to Google and other search engines.
5) Relevancy. If the web page the backlink is coming from is centered on scrapbooking and the backlink leads to another site about scrapbooking, the backlink has far more value than if it leads to a website about exotic cars. Google weighs the value of all incoming links to a website, link building SEO is about building links which work jointly in concert around a common related theme.
While these are some of the most important factors to link building SEO there might be other smaller factors you could take into consideration.