Apple's iMessage service has been delivering texts to your iDevice of choice for a while now (at least, when it's working properly). But those messages have traditionally been limited to other fellow iOS and Mac users. If you wanted to keep tabs on SMS messages from folks on Android or other operating systems, you had to dig out your iPhone to peep those green chat bubbles. Ugh, so inconvenient.
With iOS 8 and Yosemite, you can sync up that process so all messages, no matter what OS the sender is on, get delivered to your iPhone, iPad, and even your Mac. To do this, you need iOS 8.1 installed on your iPhone and OS X Yosemite on your Mac. You also need to be logged into the same Apple ID on these different devices.
On your Mac, open up Messages then go to Preferences > Accounts. Select your iCloud account and make sure that Enable this account is checked, and that your phone number is checked underneath the You can be reached for messages at: header.
Now on your phone go to Settings >__ Messages__ and tap Text Message Forwarding. Now you'll see a list of devices connected with your Apple ID. Toggle on the ones you want texts forwarded to. Once you do that, a message with a six digit code will pop up on your iPhone, and you'll be prompted to enter that code on your Mac or iPad. Enter the code, and text messages should forward to the device whenever they're sent to your phone number.
If at some point in the future you change your mind about this whole text message forwarding thing, just go back into your phone settings and toggle off the devices you don't want text messages sent to.
