The latest version of Android - version 4.3 comes with some under the hood improvements. It comes with a new autocomplete system in dial-pad that was said to come a long time ago, and also sports some new features like Bluetooth Low Energy. There's also this new Keep app which lets you take quick notes. While most of the changes are good, there's one change that you would be surprised to learn about - Android 4.3 will scan for WiFi networks even if the WiFi is switched off. This is done for providing better location information to apps.
However, not everyone will be happy with this and that's why there's an option to disable this feature. It's somewhat hidden but here's how to locate it.
Disable WiFi scanning always available on Android 4.3
Step 1: Launch the Settings app and tap on Wi-Fi under Wireless & Networks. Next, tap on the menu button located at the bottom-right corner of the screen and select "Advanced."
Step 2: This will open Advanced Wi-Fi screen. From here, remove the checkmark from "Scanning always available."
That's all you need to do. Now your phone won't scan for WiFi networks at all times.
As per the instructions written under the option, this option helps in letting Google's location service and other apps to scan for networks whenever required. It might improve location service accuracy, but you'll need to decide whether you need this option enabled or disabled. By default, this option was disabled in my case, but you might need to check it out on your device.