SEO, Search Engine Optimization, simply is a techniques when implemented improves the visibility of a website in a search result pages. This means that it helps to rank the site higher than other millions of sites in response to a certain search query. Thus it helps to get traffic from search engines. This techniques may be broadly categorized into two:
White-Hat SEO: The techniques that are recommended as a part of good design and are considered safe and produce long term results are called White-Hat SEO.
Black-Hat SEO: This refers to the use of aggressive SEO strategies, and techniques that focus only on search engines not human audience and usually doesn't obey search engines guidelines. When these techniques are implemented, the website can suffer a ranking penalty; worst of all, the website will be removed from the index.
Therefore, it is wise to implement White-Hat SEO inorder to avoid such issues.
For the optimization, we can do it in two ways:
On-site optimization: This optimization involves optimized website pages, titles, tags, content and overall structure for the target keywords. Therefore, in onsite-optimization, we optimize concerned website only for the target keyword.
Off-site optimization: This optimization involves generating significant inbound links from highly respected external websites. In off-site optimization, links are generated through different ways like from forum posting, social bookmarking, blog posting, blog commenting, directory submission, etc.
Every people who have insufficient knowledge in SEO, they argue that On-site Optimization is most than Off-site Optimization. They believe that even if there aren't significant referral links to the concerned website, it doesn't matter, On-site can help the website to rank in the front with the targeted keywords. But in reality, SEO Experts express their opinions that both on-site and off-site are equally important, they both determines what the website is about and how much value should search engine give when the query is processed in the search engine.