（Cases mentioned in this chapter: Airbnb, Instagram, and Evernote)
1. Product market fit
Growth hackers believe that products (even whole business and business models)can be changed until they are primed to generate explosive reactions from the first people who see them. The best marketing decision you can make is to have a product or business that fulfills a real need.
AIRBNB started as a way for the founders to turn the living room of their apartment into a little bed-and-breakfast， and offered breakfast to the guests. It was named air bedandbreakfast.com in the beginning. After adusting and repositioning, the founders first add networking ideas into the booking website.It was a better market, but the founders sensed they could improve the idea further. They decided to abandon the breakfast and networking parts of the business, redifining the service as a place for people to rent or to book any kind of lodging.
(I think especially networking really make the customer base narrower. Many people who are travelling with their family, they dont want to join any social networking. After abandoning the networking, the consumer scope is expanded largely).
Airbnb went from a impratical idea to an explosive and pratical idea, then as a result, a billion-dollar valuation.
Instagram is another good example. It started with a location-based social network called Burbn. But, after launching the app, the founders found that their users only flocked to one part of the app --- the photos and filters. Then, the founders soon decided to turn Instagram to the app as we know it now: a mobile app for positing photos with filters.
There is no secret sauce. Some companies just spend a long time trying new iterations until they achieve Product Market Fit --- to have the product and its customers in perfect fit with each other.
The best way to get PMF: start with a minimum viable product, and improve it on the feedback. (Eric Ries, The Lean of Start-up)
Marketers need to become the advocate for the potential market, figuring customers needs and designing a product. The marketer should become the translator who builds the bridge between the producers and customers.
2. How do you get PMF ?
Like some authors, they test their book ideas on youtube or other blogs, checking the comments and reponses from the readers. They ask readers what they would like to see in the books.
There are easy tips:
1） writing hypothetical prss release
2 ) Define the crucial parts of the user experience by making mockups of pages
3) try to write the user manual, including 3 parts, concepts, how-to and reference.
3. Open up to feedback
Take marketing off the table.
EvernoteThe company decide to delay spending on marketing for the first few years of its growth. Evernote took marketing off and pour the budge into product development. This does not mean that you could not do anything. Evernote also came up with some tricks to get people to know their products. 我们不再是无助的，我们不再盲目地把产品卖给那些没有共鸣的人。我们可以利用得到的信息。相反，我们可以利用得到的信息去提升产品本身，最终我们可以refine our idea into something that can in many ways sell itself. Marketing is a waste of time without PMF. Of course, there are many tools to get there.
TOOLS: Make surveys with Surveymonkey, wufoo, qualaroo, or google docs to some or all of you customers, dont ask random people or your friends.Ask questions like: what is it this product brought you to the product ? what is holding you back from referring the other people to it ? what is missing ? what is golden ?