to catch a fish you need bait

As the title suggests in business how do you catch customers...
Well all business needs to have an online presence period. For now I'm talking apps. Why do you need an app? When you have an app and more and more people download it, the big advantage is that you can send messages directly to your customers smart phone screen called "Push Through Notifications". 
When you send these messages the big advantage is your customers read the messages as they would have opted in to receive your messages in the app. 
When its done this way its "not spam", and it will have a higher conversion rate to increase footfall into your premises because your clients are obviously interested in getting special offers from you.