During the Google I/O conference held in 2014, Google presented its new design guidelines for Android graphical aspect. It was called Material Design and was integrated into the OS for the first time with Android Lollipop, replacing the previous Holo, and ended up landing on all the applications belonging to the Google family: Gmail, Drive, Calendar...
All your Android apps, no with Material Design
The thing is that not all applications take on the same design concept. That's obvious because they're not all developed by Google. But if you love this graphical concept, you can adapt them all to Material Design thanks to MaterialOS.
It's a theme developed by the members of the long-lost CyanogenMod community that comes along with images and icons for this mobile operating system inspired by Google's guidelines and that tries to bring this Material Design to all the apps installed on our phone. At least it tries to.
Thus, here we'll find an interesting tool to make our Android as homogeneous as possible in terms of design, especially appropriate if you rate aesthetic standards highly.