Your Mac can function as a wireless hotspot, allowing you to connect your other devices to it and share its Internet connection.
This is most useful if your Mac is connected to a wired network interface via Ethernet. You can connect your wireless devices to your Mac and share the wired Internet connection with them.
Enable Internet Sharing and Configure Your Hotspot
The Wi-Fi hotspot option is part of the “Internet Sharing” feature in Mac OS X. You’ll find it in the System Preferences window. Click the Apple menu, select System Preferences, and click the Sharing icon.
Select the “Internet Sharing” option in the list. You’ll now need to select the Internet connection you want to share with the devices.
The one big limitation is that you can’t both be connected to a Wi-Fi network and host a Wi-Fi network at the same time.
In the “To computers using” box, enable the Wi-Fi option. This will create a Wi-Fi hotspot, and the Internet connection you selected at the top of the window will be shared with devices that connect to the Wi-Fi network.
Click the “Wi-Fi Options” button at the bottom of the window to configure your Wi-Fi hotspot. Select your preferred network name and the best Wi-Fi channel.
Be sure to click the “Security” box and select “WPA2-Personal” and provide a password. By default, the hotspot will be configured without a password and anyone will be able to connect.
When you’re done setting things up, click the checkbox to the left of Internet Sharing and click Start to activate your Wi-Fi hotspot.
If You Want to Share a Wi-Fi Connection
Sharing a Wi-Fi network connection by creating another Wi-Fi network will require a separate physical network interface, such as a USB Wi-Fi adapter.
You could also just create a Bluetooth PAN (Personal Area Network). Connect to the Wi-Fi and tell your Mac you want to share the Wi-Fi connection over a Bluetooth PAN. If your other devices have Bluetooth, you can pair them to the Mac and wirelessly share the Wi-Fi connection over Bluetooth.
A Bluetooth PAN can take a bit longer to connect to — thanks to the Bluetooth pairing process — and can’t reach the speeds of Wi-Fi. However, it is also a bit lighter on your Mac’s battery life, so it’s not all bad.Your Mac’s physical Wi-Fi interface can either be connected to a Wi-Fi network or host its own network. It can only do one of these things at a time. This means you can’t be both connected to a Wi-Fi network and sharing that Wi-Fi network’s connection over Wi-Fi.
Windows has a useful feature that allows you to create a virtual Wi-Fi adapter interface, making it possible to both connect to a Wi-Fi network and create a Wi-Fi hotspot using the same physical network interface at the same time. This feature is hidden, but you can access it using the Virtual Router software — this uses the same Windows features as Connectify, a commercial application.
Macs unfortunately don’t have the same sort of virtual network interface feature. To share a Wi-Fi connection over Wi-Fi, you’ll need a separate physical Wi-Fi interface.