Mockup is a visual representation or prototype of a product or feature. It's like a sketch or blueprint of what the final product will look like. In product management and software development, mockups are used to give stakeholders a clear idea of the design and functionality of the product before it is fully developed. It helps teams align on the vision and make important decisions early on. Think of it like a mock cake made of cardboard and icing - it's not the real thing, but it gives you a taste of what's to come.