There are a lot of Bullet Journal iterations out there today but Ryder Carroll is the originator of the Bullet Journal practice. According to the below video, he calls #bujo “an analog system I devised that will help track the past, organize the present, and plan for the future.”
I've dabbled in his Bullet Journal a bit but haven't nailed it just yet. Thankfully, Carroll released a new book aptly titled The Bullet Journal Method: Track the Past, Order the Present, Design the Future (Amazon) to further explain the process and how it helped him become consistently focused and productive. You can download a few of the chapters for FREE right here.