Nir Eyal

The cold truth is that the best products don't always win. Many times it's - the products that have the ability to keep users coming back and using them without conscious thought and using them out of habit are the ones that keep us coming back.

The market for religious apps is fiercely competitive; searching for 'bible' in the Apple App Store returns 5,185 results. But among all the choices, YouVersion's Bible, funded by LifeChurch.tv of Edmond, Oklahoma, seems to be the chosen one, ranking at the top of the list and boasting more than 641,000 reviews.

Every time you log in to Facebook, every time you click on your News Feed, every time you Like a photo, every time you send anything via Messenger, you add another data point to the galaxy they already have regarding you and your behavior.