After Web 2.0, Here is SEO 2.0.

SEO SEO 2.0
Link building, manually adding them, submitting static websites to directories, link exchange, paying for links Getting links, enhancing it by certain actions like blogging, writing pillar content, creating link bait, socializing
On site optimization for spiders: example repetitive page titles concentrating (solely) on keywords On site optimization for users. Example: Kick ass post titles
Competition: You compete with others to be on the first page/in the Google top 10 for keywords Cooperation: You cooperate with each other submitting fellow bloggers to social media or voting for them, you link to them
Barter: You give me link and only then I will give you one Giving: I link you regardless whether you link back, but in most cases you will, more than once
Hiding: We’re not doing SEO, we can’t show our client list publicly, impersonal SEO company Being open: Welcome our new client xyz, we are proud to work together with them, Rand Fishkin and his team
keywords tags
Optimization for links Optimization for traffic
clicks, pageviews, visits conversions, ROI, branding
DMOZ del.icio.us
Main traffic sources: Google, Yahoo, MSN Main traffic sources: StumbleUpon, Niche social news sites, Blogs
one way communication dialog, conversation
top down bottom up
undemocratic, who pays most is on top democratic, who responds to popular demand is on top
50% automated 10% automated
technocratic emotional

From: http://seo2.0.onreact.com/seo-vs-seo-20-top-15-differences

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