These links are important to promote SEO for a site, but it's also important to look at the internal links - those links that are already located within your website.
Internal links sometimes gets overlooked, but can help your SEO immensely.
You really should be taking care of your internal links before working on external ones.
There's times when a site with a better internal structure gets ranked hirer than one with a poor internal structure with a number of external links.
The great thing about internal links is that they're coming from an authoritative site which is your own.
Authority is something that external links sometimes lack.
Internal links are used by search engine spiders to see what is on all of your pages.
So you'll want to build the content on your website by using keywords you're targeting through out it.
When you increase the page rank of your internal pages it will overall increase your site's ranking.
If your website has been on the internet for a good amount of time, it tends to get better SEO than others because it has a history of internal links that search engines use.
If your website is newer, it will take time for the results to take effect, but it can definitely be ranked higher through internal links if done correctly.
Also, remember that not only should keywords be put into your content, but should be put into file names as well.
SEO keywords should cover codes, tags, anchors, picture files, folder names, etc.
It isn't just limited to the content of your website.
If you place an image on your website and it's named "1023940.
jpg" then the search engines aren't going to read it.
But, if you named it "onlinebirthdaycards.
jpg" for your on-line birthday cards website, then the search engines will be able to pick that up and rank you better.
Internal linking is important to get all of your pages found by search engine spiders.
It's useless to have 40 pages throughout your website if only six of them are being found.
Keep internal linking in mind in your SEO efforts and internet marketing techniques.