Remote Apple Events: Built into the Mac are tools for automating tasks on your computer. Many such tasks are created with and executed by something called AppleScript. When you enable this sharing preference, you're telling your Mac to accept actions (or "Apple Events") sent from another computer on the network. For example, an Apple Event might tell your Mac to print all the documents within a particular folder on your desktop. As before, you can choose who you grant this power to. And yes, leave it off if you don't understand or need it.
Internet Sharing: Suppose you're in a hotel that offers a wired Internet connection rather than Wi-Fi. You can plug your MacBook Pro into this connection to get on the Internet, but what about your Wi-Fi iPad? If only you could somehow share the Mac's connection...
You can, and Internet Sharing is the way. In our scenario, choose Ethernet from the 'Share your connection from' pop-up menu, and select Wi-Fi in the 'To computers using' list. Or in English, "Hey, my Mac's connected to the Internet via an ethernet cable. You're welcome to share that connection with your iPad over Wi-Fi."
When you switch on Internet Sharing, you'll be asked if you really want to do this (of course you do). Click Start. The Wi-Fi icon in the menu bar will turn gray and display a white upward-pointing arrow, indicating that it's sharing its Internet connection. On the device you wish to use to glom onto that connection, open its Wi-Fi settings and choose your Mac as the hotspot.
If you don't want everyone and her brother sharing this connection, click the Wi-Fi Options button at the bottom of the Sharing window before you enable Internet Sharing. In the sheet that appears, you can name the network, choose a channel (you're safe leaving it at 11), and select the kind of security that you wish to use ('None' or 'WPA2 Personal'). If you choose to use security, you'll have to enter and confirm a password for your network.
Bluetooth Sharing: Bluetooth is a short-range networking scheme that lets you do things such as broadcast music from your iPhone to a set of wireless headphones or to a car's audio system. Wireless mice, trackpads, and keyboards also use Bluetooth to send their signals to your computer.
You can also share files over Bluetooth, a capability that can come in handy if you have a couple of Macs that you can't network in another way (because there's no Wi-Fi available, for example). This is how to do it.
First, enable Bluetooth Sharing. Once you've done so, you have some decisions to make. One is to figure out how to handle an item that you receive as a Bluetooth transfer. You can automatically accept and save it, automatically accept and open it, receive a prompt to manually accept or decline it, or never allow such transfers. You then select a folder where you'd like transferred items to appear (Downloads is the destination by default).
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