Sahil Lavingia, founder of Pinterest:

Design is shrinking the gap between what a product does and why it exists. Designing is not just about picking the right font or gradient. Stop thinking about design in terms of wire frames or visual style; it is about the product as a whole. Designing is figuring out the purpose of your product and how you orient everything else around it. And that means that everyone within a company plays a role in the design process. And that means that everyone in a company needs to learn design literacy. It’s a hard task.