We are not buying software on CDs anymore. In the modern age, the software for our personal computers and mobile devices is sold from the specialized online application stores. All leading players of the IT industry created their own app-stores for their platforms. Therefore, we have Apple's App Store, Google Play, Microsoft's Apps for Windows, and so on... In a short time frame, these application stores become a home of hundreds of thousands of applications developed by various developersworldwide and served billions of application purchases and downloads. That's really impressive and it really changed the way we find, download and install software.