They are both effective.

I have to say, after years of spending a lot of time "tweeking" my site, getting links, and doing the thousand and one things that are recommended for good SEO, I've found onsite optimization is far better than offsite.

The single most important thing is that your site contains relevant, current, up to date information on your site's subject. That's new articles, not simply new comments on old articles.

If your site is linked to by thousands of others with scant regard to who is linking too you, then Google doesn't rank you very highly (if at all).

However, if your site contains information that others want to read, then others with relevant sites will link to you, and Google will rate your site.

So content ... good content ... new content ... more content. Content is everything.

THEN ... make sure your titles and keywords and descriptions match your brilliant content.

You need to make sure your website is search engine friendly by performing onsite optimisation but you also need to do off site optimisation so you can aquire quality back links from relevant sites.

Thanks for the info

I dont know for sure but i think its off-site SEO, becouse it drives many traffic other than on-page SEO

both of them work parallel, because you have to cover both the part of seo.. and link building is about meaningless if you dont have on page optimization...

A combination of both on page and off page will allow you to rank well and achieve your goals. IMO doing one without the other is a pointless task.

I agree with Wragh, you can't get results if you will neglect any one from them.

The algorithms of search engines change frequently and no one can say what they will be in the future but currently there is parity in the importance of onpage SEO and offpage SEO. Keywords will always matter but quality backlinks are even more important. Getting good search engine placement without quality backlinks is very hard.

The best approach to SEO is to combine onpage and offpage factors. The fact that it is possible to get decent rankings with keyword optimization only doesn't mean that this is the way to go. Relying only on backlinks is also not a good idea. The winning strategy is to apply both onpage SEO and offpage SEO and hope that this will affect search engine placement in a positive way.

Both are effective.If you have a good content, then you can try for On page.It will help you to get high PR.Off page is required to get more back links, more visitors.It will also help to get better indexing in Google.