If your Mac is connected to the Internet through a wired connection, you can share this connection with your iPhone via Wi-Fi, so you can use both devices online at the same time. After changing your Internet sharing settings in Mac OS X and choosing a name and password for your Wi-Fi network, you can connect your iPhone to the Internet and use it online as long as your Mac is running.
Sharing Your Internet Connection From Mac OS X
Launch System Preferences from your dock and select "Sharing" under "Internet and Wireless" to open the Internet sharing settings.
Select "Internet sharing" from the list of services. Choose the wired connection you want to share with your iPhone via Wi-Fi from the "Share your connection from" drop-down menu. For instance, if your Mac is connected to the Internet via Ethernet, select "Ethernet."
Tick the "Wi-Fi" check box under the section entitled "To computers using:" to indicate that you want to share your connection via Wi-Fi.
Click "Wi-Fi Options..." to adjust the settings for your network. Type the desired network name and password in the "Network Name" and "Password" fields. Click "OK" to start sharing your connection.
Connecting Your iPhone to the Internet
Tap "Settings" from your home screen and select "Wi-Fi" to access the Wi-Fi settings on your iPhone.
Select the network you created from your Mac from the list of available networks.
Type the network password when prompted to do so and tap "Join" to start using your iPhone online.
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