Sony Xperia Z2 has a nice simple UI through which you can do a lot more thing. The UI is designed with a motive to increase productivity. It is easy to customize and has many options that can be helpful. Favorite bar is the part of UI. This bar brings you some apps that are very quick to access. Like onscreen calculator, browser widget, screen lock, screen capture, etc. This favorite bar is accessible by pressing the menu key. Just hit that and it appear on the bottom part. Now you can modify that and add your own application in it. You can keep the home screen clean if you want with minimum things. The favorite bar is very handy to use. You can add bookmarks, app shortcut, etc on the same and access them with one tap. At first I thought this would not be editable. It will only work with set of small apps and shortcut it already has in the settings/widget or by downloading apps from Google Play. But you have option to add many things on it.
Tap on the menu key to start the Favorite bar.
You can see a tiny arrow at the start. Tap on it. This will maximize the favorite bar and you can see already a few app shortcut in it that you can add with one tap. Like Chrome.
To add tap on the app and drag it on the Favorite bar. The icon is added.
To add more you can see a + icon on the top side. A additional menu appear to add small apps. you can directly add different apps from Playstore or simply from the widgets.