If you want to get high rankings on search engines then you have to consider many different factors.
On-page factors and off-page factors
Regarding on-page factors, the content of your web pages is important, the position of your keywords in your web page elements is important, the keyword density matters and much more.
When it comes to off-page factors, the number of the links that point to your website is very important. It's also important that the the links to your website contain your keywords and that the links are from related websites.
All of these factors are important. However, there is another factor that is even more important than the other ones. That single factor will determine whether your search engine optimization activities will be successful or not.
A single factor is more important than all other factors
You might have lots of inbound links with the anchor text "my great product" and your web page might be perfectly optimized for the keyword "my great product".
You might even be number 1 on Google for the keyword "my great product": if the wrong people or too few people search for that keyword then your SEO efforts will be in vain. The most important factor that decides whether you succeed or not are the keywords that you choose for promoting your website.
If you target the wrong keywords, you'll waste a lot of time, energy and money.
Source:Succesful-SEO
