Quick settings in Android are a very handy feature and allow you access to the most used settings without having to leave the app you are currently working in, these settings include things such as WiFi.
How to use Quick Settings in Android
Accessing Quick Settings
Accessing quick settings is as simple as swiping down from the top of your screen with two fingers, this puts the notifications drawer at the bottom of the screen and takes you directly to quick settings.
Depending on what version of Android you have you may still have to jump into the settings app for a few things, but from Android 5.1.1 Lollipop you can do pretty much everything without having to go into the settings app.
In 5.1.1 you can tap on the services icons e.g. WiFi, to turn them on or off, and you can tap below the line on the text, to change which network you are connected to.
In older versions you can tap the WiFi icon but you will be taken to the WiFi settings page where you can change networks or turn WiFi on or off.
Some of the other settings you can adjust in Quick Settings include Airplane mode, Bluetooth, Auto Rotate, Location services, Screen Cast, and your brightness.