Last week I showed you how to connect your Mac to the Internet and to a local network. Now that your computer is on speaking terms with other devices and services, let's examine exactly how you can put those powers of communication to use for sharing the devices and files associated with your Mac.
Sharing options for nearly everyone
To share elements of your computer with others, you must first grant permission for certain kinds of sharing to take place. You do this via the Sharing system preference, which you'll find in the Internet & Wireless section of Mountain Lion's System Preferences window. Once you've selected Sharing, you'll see a number of options. We'll start by looking at the ones you'll use most frequently.
Screen Sharing: This feature lets you remotely view the screen of another Mac on your local network, as well as optionally control that Mac. It has been part of the Mac OS for quite some time, and with Mountain Lion it's dead simple to use.
To allow someone to share your screen, you must first make the option available. To do that, open the Sharing preference and enable the Screen Sharing option. Once you've enabled Screen Sharing, you can designate exactly who may exercise this privilege.
By default, only people who have an Administrator's account can share your screen. You can also allow specific users or groups from your list of contacts to screen-share with you. To do this, confirm that the Only these users option is selected, click the plus (+) button, choose Contacts or groups in the contacts sheet that appears, and click Select. This action will add them to the list of users who can request screen-sharing access. If you enable the All Users option instead, anyone who can see your computer on the local network can share your screen.
To share your screen, all that someone on your network need do is select your Mac under the Shared heading in a Finder window's sidebar and then click the Share Screen button that appears near the top-right of that window. The person will be prompted to provide an approved username and password for the shared Mac. Alternatively, the would-be sharer can enter the Apple ID associated with that Mac. Simply clicking Connect completes the connection. We'll discuss the ins and outs of screen sharing in another column.
File Sharing: If you enable File Sharing, others on your network can, well...share files with you. Setting up this arrangement doesn't entail granting them complete access to your Mac. Rather, it allows them to copy files from their Mac into folders on your computer that were created specifically for sharing. By default, one such folder exists for precisely this purpose. It's called the Drop Box folder and you can find it by following this path: youruserfolder/Public/Drop Box. Each user account has such a Drop Box folder.
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