@mitu
Note for WiFi on the new Raspberry Pi 3 Model B+:
WiiFi is disabled until wireless regulatory domain is set (Pi 3 B+ only)
The domain can be done through 'Raspberry Pi Configuration' (rc_gui),
'raspi-config' or by setting 'country=' to an appropriate ISO 3166
alpha2 country code in /etc/wpa_supplicant/wpa_supplicant.conf.
US= United States
GB= UK
Example by another user of what it should look like (with GB country code)
country=GB
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
network={
ssid="myssid"
psk="mywifipassword"
}