If your brother or colleague should also be allowed to use your WLAN (or that of your favorite library or regular pub), the password can be easily shared under Android via QR code. […]
The password for your WLAN access should be as good as possible. Preferably one with 20 digits and a wild mix of uppercase and lowercase letters, special characters and digits.
If your colleague should also be able to use your WLAN, in which you are currently logged in, you can save the person the error-prone entry of a long password by sharing the password via QR code. This works if you both have a smartphone with Android operating system.
Solution: On the Android smartphone, open the Settings app and go to a point in it like Network &Internet, see in the screenshot (A). Tap directly on the command name WLAN (B). After the name of the wireless network you are currently connected to, tap the gear icon (C).
Via network & Internet it goes to WLAN. Behind it, tap the gear icon Source: PCtipp.ch
Now you will discover a QR code icon with the Share command (D). Tap on it. Now both the QR code (E) with Wi-Fi access, as well as in small font, including the human-readable password. If someone wants to connect a laptop to the Wi-Fi, he can select the Wi-Fi and type the password.
A QR code can be displayed via sharing. The person who wants to connect their Android device to the same WiFi accesses Settings/Network & Internet/WiFi and taps on the QR code icon behind Add WiFi Source: PCtipp.ch
If someone wants to connect to the WLAN with an Android smartphone, it goes like this: Also open Settings/Network & Internet/WLAN. Behind Add Wi-Fi, tap on the small QR code icon (F). Now you can scan the QR code that is emblazoned on the display of the other, already connected Android device.
How to make a Wi-Fi password accessible to another iPhone with one iPhone, read here.