Off page optimisation, or external links to your website, is the most important bit of SEO. With out this, you will have a very low chance of ranking in Google or other search engines.
A long time ago, Singapore SEO consultants would just spam a websites with links no matter the quality. Previously, what mattered most was the quantity of the links and webmasters would just constantly spammed all around the web for links to their sites.
However, times have changed, now if you were to spam, the chances are that your website will not be in a favorable position. What matter most currently is the quality of the links to your sites, as well as the optimisation of the achor text of the link. Here’s another article about SEO.