Do you browse the Internet early in the morning or late at night? If "Yes" then you may be facing the same problem I faced. Which is when you open your browser, that white background light hit your eyes also the same when you open a new tab every time and its feel like shit.

WhatsApp users on Android can now use the voice-calling feature and no need of invitation. The voice-calling feature rolled out in February, but only a small number of people are able to use it and expand it by invitation-only by the people who already using it.
But now it's available for all Android user and no need of invitation. Just update to latest WhatsApp version which is Version 2.12.19 

HOW TO INSTALL APK or ANDROID PACKAGE FILE TO YOUR ANDROID PHONE 

Google play store is the best place for Android apps, which contain more than 1 million+ apps. But what happened when the app store pulls an app from it store. Yes, Google does it because of many reasons and also sometimes updated version is not available in Google stores as soon as it releases. So, is there any other options that we can install updated version of the app even it's not available in the Google app store or can we install the app which is no longer available in Google app store. The answer is simple "Yes" and the process is known as "sideloading".