Start64!Microsoft today began offering a 64-bit version of Office for Mac to users on the Production channel. It was originally offered to Office Insiders back in July as version 15.24. Today's update is 15.25, which Insiders have had for a couple weeks.

Ever since Apple released Mac OS X 10.7 Lion back in 2010, the company's desktop OS has only supported 64-bit Intel processors; however, until Microsoft announced 64-bit Office, the productivity suite has only been offered in 32-bit. As Microsoft says, "unlike Windows, there is no choice between running a 32-bit or 64-bit version of the operating system."

Because of this, Microsoft will not continue to offer a 32-bit version of Office for Mac. Once each channel has transitioned to 64-bit, that's all that will be available.