Apple Time Machine feature is just outright simple and like all things Apple it just works. It does not the advanced feature set of some of the other back up services for Windows, but what it does it does really well and works almost every time, that too flawlessly. So what is Time Machine? If you connect an external hard disk to your computer, Apple's Time Machine service will back up your entire computer (you can specify files that you do not want to back up) automatically and periodically. After the long (time for the first time back up depends on the amount of data your Mac has) first time backup, it only does incremental backup afterwards. This saves a lot of space on the external hard disk. Then when you want to look up a specific file or a specific version of a file, that might have been deleted by mistake or modified by error, respectively, using Time Machine (with a fancy looking interface), it is a cakewalk. See Apple's brief setup video for Time Machine.
For doing this, any external hard disk that connects to your Mac with a USB or Thunderbolt or FireWire or some other way using an adapter will suffice. But with everyone yearning to cut the chord nowadays, isn't there a more elegant solution or wireless backup? Of course. Apple has a product called AirPort Time Capsule. It has a 2TB or a 3TB hard disk built in and also acts a wireless base station. So it is an effective router replacement with an inbuilt hard disk and can be used for Time Machine backups. However Apple's TimeCapsule costs 2X or 3X or sometimes even more, purely interns of cost/GB. Though this is not a fair comparison as the TimeCapsule can also be an excellent router, what if someone needs wireless backup but do not want an Apple router or in my case, I have a older AirPort Extreme (Apple router with no in built hard disk) and do not want to shell another $300? Can you somehow use an external hard disk, like the ones from Seagate and Western Digital to use for Time Machine backup, wirelessly? The answer was not easily available, at least not when I wanted one.
A mac, of course, an external hard disk (I would suggest at least 1TB so it is future proof when the data size grows or the number of Mac users grow), an Apple AirPort Extreme (or this should work even if you only have an AirPort Express) and wireless Internet.
My Mac is a late 2011 13" Macbook Pro (with a DVD drive). I have close to 200GB of data in it. After some research I bought a Seagate Expansion 2TB Desktop External Hard Drive on Amazon for $80 (a 2TB AirPort TimeCapsule retails for $299!). I am biased towards Seagate as I have used their hard disks for ages and have a very good experience with them. I have an Apple AirPort Extreme (2012) version, the flat disk like one, not the recently updated tower version. With these I set out to get my own wireless Time Machine backup service.
Wireless Time Machine backup
The first thing you want to do is make sure that external hard disk is formatted for use with the Mac. Also Apple suggests that the drive used for Time Machine backup be dedicated or not to use for anything else like manual data storage. Since I have setup this 2TB Seagate drive as a wireless backup for Time Machine already, to demonstrate the process here again, I am using a smaller Seagate external hard drive that I could spare.
1. Connect the external hard disk to the Mac and open Disk Utility.
2. Select the external hard disk in the sidebar on the left (select the primary indent and not the sub indent below).
3. Select "1 Partition" in the Partition Layout, select "Mac OS Extended (Journaled)" in the Format, type in a custom Name for your TimeCapsule and click on "Options" in the bottom of the pane.
4. In the "Options" pane, select "GUID Partition Table" and click "OK". And now back in the main panel, click "Apply". Beware that this will erase the entire hard disk of its contents, if any and free it up to its full capacity.
Now the external hard disk is ready for setup as a TimeCapsule for wireless Time Machine backup. Once this process is done, a hard disk icon with the custom string name that was given during the formatting of the external hard disk should appear on the desktop (Check the Finder's preferences if this icon does not show up on the Desktop as "Show External disks" should be checked).
5. Once this icon shows up, right click on it and eject it as the hard disk now needs to be connected to the AirPort Extreme using a USB cable in my case.
6. Once the external hard disk is connected to the AirPort Extreme, it should show up in the Finder under the AirPort Extreme pane, as shown below. Now head back to Time Machine and turn in ON and hit "Select disk".
7. In that the external had disk named "Time Capsule" (in my case should show up) and select that.
All set now. The first back up might take a few hours depending on the data being backed up and the speed of the wireless network. For example, my approximately 200GB of data took around 7 hours with a decent Comcast wireless speed to backup.