A backlink is a link that compiled script contains the address of a web / blog, which were mounted to a particular site. Why do we have to build a backlink? because the backlinks themselves have benefits to increase our page rank in a search engine like Google, Yahoo, Ask etc..
Internet network in the world is often called "the web" or the term net profit - profit. Net profit - profit is formed by a thread - the thread that created by the spiders. When the greater width of broad net profit - profit, then the number of prey that would be obtained even greater.
Picture that illustrated how can I make a system where a backlink to work on the internet. Suppose that our website can be compared to a net profit - profit. While we assume backlinks yarn - yarn net. With extensive network of backlinks then proportional to the status of our page rank. The more extensive our backlinks the higher the Pagerank that we get.
To get a certain page rank backlinks we need a certain amount of page rank [... ] Backlink. Suppose we want to get a pagerank 5.
To Get a PageRank 5 requires a backlink from a page rank third as many as 555 backlinks. Getting to require a backlink from a PageRank 5 PageRank 6 backlink number 3.
Backlink alone there are 3 types:
a. One-way backlinks: which links are obtained from a website or blog while the site we do not provide a link to a website or blog. Suppose you give a comment on another website or blog, create a signature in forum discussions, backlinks from classified ads for free, and others.
b. Two-way backlinks: or call each other that link, or link exchange. Where our website provides links to other people's sites, and other people's sites and even then provide a link to our site.
c. or Three Way Links, where links are formed from three sites. For example the A site providing links to site B, site B links to site this gives C, C sites provide links to A. Backlinks like this is rather hard to come by, unless we use the services of SEO or create a bond between the owner of a web or block to create this three-way Links.
Or it could be a dummy blog, you created three blogs, continues to create this three-way link.
Of the three types of backlinks on What is the best? answer of course is a one-way backlinks, but the quality. What I mean here is a quality backlink
one direction is obtained from the web or blog are high rank and dofollow. The important thing here is dofollow, why? Because dofollow links from sites that this is considered by search engines, links from sites that nofollow useless we can be even higher pagerank of the site but did not provide significant benefits for our blog.