Search Engine Optimization (SEO) is the process of improving a website’s search engine rankings for selected set of keywords or key phrases. SEO stresses upon the search habits of the end user/searcher to derive the keyword set. The process of SEO involves a series of steps/activities and one of the most important elements of the entire SEO spectrum is Link Building, also known as off-page optimization.

Link Building aims to increase Link Popularity, which is nothing but the no. of inbound links pointed to your site. Search engines such as Google, decide importance of your site on the basis of a series of parameters, an important one being link popularity and quality.

"Links reflect value on the web". They always have two types of audience: visitors and search engines. Good quality links (which are relevant, contextual and derive from search engine recognized sites) can be generated by using many link building strategies. Let’s have a look at some of them -

1. Reciprocal links: When links are exchanged between two sites, they are termed as reciprocal links. In reciprocal link building, link value passes to both sites involved in the exchange. This link building service was used predominantly by SEO’s till about a couple of years back.

2. Three way links: (links ring): These are variants of reciprocal links. In this method 3 websites are involved and the link pattern is typically A->B->C->A. Though not the most popular, this method can be used to avoid duplication.

3. One Way Links: One way link building is the most effective and profitable link building technique provided by many link building services. In this form, a link is generated from another site without having to link to the other site. As one way links represent natural link building phenomenon, it is valued more than other expert link building services. There are different methodologies used to generate one way links such as:

a. Paid or Free Directory Listing: This type of link is obtained by acquiring a listing on a paid or free directory, where in a directory is normally a collection of manually moderated website/business listings.

b. Article Submissions: Articles which are submitted to various free and paid article submission websites allow targeting back links to the submitter’s/Author’s website.

c. Social Media Link Building: Social Media sites such as News and Bookmarking sites for .e.g. Digg, Del.icio.us etc. provide an excellent opportunity to target one-way incoming links through posting of generic public related news items/bookmarks.

d. Blogs: Blog Posts and Reviews are excellent techniques to generate valid content based one-way back-links to your website.

e. Text-link Ads: Link Ads, derived using negotiations with webmasters amount to quality one way links through important pages of websites, such as the homepage.

This certainly isn’t an exhaustive list of Link Building Techniques, however it definitely does cover a number of strategies which have been proven to be effective link building techniques.