In his book Contagious: Why Things Catch On, Wharton business school professor Jonah Berger lays out the six key elements that make ideas and products catch on.

Berger was inspired by Malcolm Gladwell's Tipping Point:

http://www.businessinsider.com/the-science-of-going-viral-2013-3

Below I include notes from Eric Barker's article about the book.

1) Social Currency: “We Share Things That Make Us Look Good”

“Does talking about your product or idea make people look good? Can you find the inner remarkability? Leverage game mechanics? Make people feel like insiders?”

Examples of viral videos that people want to share

http://www.businessinsider.com/how-to-make-a-viral-video-2013-3?op=1

2) Triggers: “Top of Mind, Tip of Tongue”

“Consider the context. What cues make people think about your product or idea? How can you grow the habitat and make it come to mind more often?”

3) Emotion: “When We Care, We Share”

“Focus on feelings. Does talking about your product or idea generate emotion? How can you kindle the fire?”

Vinod Khosla talks about embedding emotions in a product:

http://pandawhale.com/post/292/embedding-emotions-into-a-product

4) Public: “Built to Show, Built to Grow”

“Does your product or idea advertise itself? Can people see when others are using it? If not, how can you make the private public? Can you create behavioral residue that sticks around even after people use it?”

5) Practical Value: “News You Can Use”

“Does talking about your product or idea help people help others? How can you highlight incredible value, packaging your knowledge and expertise into useful information others will want to disseminate?”

6) Stories: “Information Travels Under the Guide of Idle Chatter”

“What is your Trojan Horse? Is your product or idea embedded in a broader narrative that people want to share? Is the story not only viral, but also valuable?”

dude.  really good stuff.  thanks.