Access denied. You do not have permission to perform this action or access this resource

Problem:
I have developed a SharePoint hosted app, and added to Host Server.
When i try to read a value from host server in App, i was getting this error:
Access denied. You do not have permission to perform this action or access this resource

Root Cause: Permissions

Solution:
Go to App
Double Click On App "AppManifest.xml"
Go to Permissions Tab
Under Scope: Select "Web"
Under Permission: Select "Read"
Save
Deploy

Now your problem is solved