At the beginning of 2013 we launched our new app AlarmNewTrack - each day it woke you up by a new track, selected according to your taste.We implemented an awesome “invite your friends” feature. The app allowed you to filter music by mood, energy, genre and year. Some filters were available by default, but if you wanted to get access to all of the features, you needed to invite a couple of friends.You could see all your friends, check them or check all of them and automatically Facebook private messages were sent to each of your friends.When we launched it, we saw that new users liked to invite all of their friends instead of checking them one by one. Our invites were sent to hundreds and thousands of friends. On average every new user invited over 5 friends. It was FANTASTIC success! Holy grail!How many active users were using the app after 2 years of viral growth?Around 10. One of them was my wife :).Where are all those tens of thousands of other users?They were killed by the terrible retention rate. Users just stopped using the service and never came back even though the average rating was 4.3.We spent all of our money on one shot and missed Retention.The moral of this story:Retention is King! Acquisition, activation, referral, revenue make no sense without Retention.In the book you'll learn the retention framework and will get 77 real case studies, examples on how businesses boosted their retention rate:Study #1. 53% response rate (250K analysis)Study #2. The #1 thing of good customer service: studyStudy #3. From 0% to 500% ROI (smart Facebook study)Study #4. How Nick hacks networking parties (example)Study #5. 80% end up purchasing (study)Study #6. $3,386 in sales from `trash` (smart study)Study #7. 335.7% higher engagement (research)Study #8. 500%-7000% ROI (+ free simple tool)Study #9. 5x revenue: The Loyal-customers frameworkStudy #10. 3.4x post reach and engagement (easy)Study #11. Ha-ha :) they know how to stand outStudy #12. 121% more leads (study)Study #13. 34% more leads (A/B test)Study #14. Free email marketing tool by GoogleStudy #15. 9 times more leads (research)Study #16. 3 stages that cost you 85% of your customersStudy #17. Over 50% of customers leave because of thisStudy #18. 5x open rate for B2B (study)Study #19. $500k in 6 months ($0 CPA)Study #20. How to stop losing 68% of your customersStudy #21. Retention: from 50% to 87% (study)Study #22. An immediate 15% reduction in churn (study)Study #23. 60% open rate for sales emails (Smart)Study #24. Blog to customers (framework)Study #25. 38% opt-in rate from a product pageStudy #26. 2x your open rates and CTR (study)Study #27. +156% to response rate easily (epic study)Study #28. 68% of people have chosen this (study)Study #29. Reactivate 58% of people (study)Study #30. 33 quotes to inspire your customer serviceStudy #31. Don`t lose 32% of your revenue (Epic secret)Study #32. Why 54% unsubscribe (and how to fix it)Study #33. 38% more engagement on Instagram (research)Study #34. +842% to email CTR (case study)Study #35. +300% more sales (very hard niche)Study #36. 56% more engagement (simple)Study #37. +42% CTR from emails (one minor change)Study #38. $5-$15 revenue per email sent (case study)Study #39. 10x more donations & engagement (study)Study #40. 9x your conversions (elephant in the room)Study #41. +750% higher CTR (case study)Study #42. How spammy is your email? (free tool)Study #43. Avoid spam folders (15 email services)Study #44. Profits have increased 16 TIMESStudy #45. Insights on how to reduce churn (case study)Study #46. One word to win back 37% of customersStudy #47. The #1 factor, customer support (huge study)Study #48. Win 91% of customers (or loose them forever)Study #49. From "no one bought it" to $10,000 in a weekEtc.