Google App is the cloud computing resource from Google where you can use their infrastructure for your web applications. You need to upload your data on Google App Engine Server and that is ready to use. It started in April 2008 with the free quota of 500MB to each user.
Now Google App Engine is going to be commercial with the option to add addition memory and resources for your web application. According to the Google App Engine blog, the free quota will also be reduced in coming 90 days and it is supposed that it will be around ~200MB but the number of page views per month which is currently 5 million will continue to be free after the 90 days announcement. Google came up with the price list for the additional resources which are mentioned below,
Price List for Google App Engine (additional resource)
The below mentioned video will explain you the App Engine Billing in a proper way,
If you liked the post, then please go for RSS subscription and follow me on twitter.