The Lean Canvas is a venture development tool created by Ash Maurya based on the Business Model Canvas by Alexander Osterwalder. It should be used early on to help you make explicit the important aspects of your venture and capture those that are the most risky and most uncertain. By filling out each of the boxes on the canvas in order, it will make clear to you the areas that need more research and validation and keep you focused on the problem that you are looking to solve. Remember that you should be a iterating on your canvas through out the life of your venture to reflect new learnings and any pivots you might make.
Create a Lean Canvas early in your venture design process and use it to guide you as you validate and invalidate your assumptions. Keep track of different versions as you learn and pivot.
The Lean Canvas encourages you and your venture team to be very clear and succinct about the problem you are addressing, how you are solving it and why you are the right team for the job.