It will be Apple's first major new product in an entirely new product category since it released the iPad in 2010. In the four years since the iPad launched, a lot has changed for Apple.
With Steve Jobs dead, this new gadget will be Apple's first opportunity to show that it can flourish without its visionary founder. As former Apple ad man Ken Segal put it, the release of this product will be new CEO Tim Cook's chance to etch his name in history.
Of course, the flip side of that is that if this product is a flop, then Apple skeptics will be out in force, saying the company is toast without Jobs.
A lot of companies have tried to introduce smart watches recently - Samsung, Motorola, LG - and yet none have really gained any traction.
Will Apple be different? Or will this be the first major flop from Apple since Jobs returned to the company in the late nineties?
Ahead of Apple's announcement, here's everything we know - or think we know - about what Apple is planning.