First off, an app store is just that, a place where you can pick and choose the apps you want to download. The app store is also a place where entrepreneurs can develop an app and with permission place it on the iPhone, iPad or Android device.
With the explosion of wireless devices, the need for a quick, central location to find information or shop online is the new business model. The app concept has captured the imagination of both entrepreneurs and users. The number of apps is growing exponentially, with more than 300,000 at last count.
Apple dominates the app store and keeps tight control on which apps are accepted on their devices.This has both advantages and disadvantages. On the plus side they can filter out unwanted apps. But such tight control can discourage developers from creating new apps.
As you might imagine, the competition for control of apps is fierce. It's a way of directing users to your device. When one company like Apple presents a new app, Google might develop a similar one for Android.
The number of apps is limitless. If you can develop a new idea, create an app and have it accepted by one of the major players, you can join the ranks of thousands of others doing the same thing.