A wireframe is a visual blueprint or skeletal outline of a website or application. It serves as a guide for the layout and structure, showcasing the placement of elements like buttons, images, and text. Wireframes help designers and developers plan the user interface without getting distracted by colors or graphics. Typically created during the early stages of the design process, wireframes can be low-fidelity, focusing on basic shapes and lines, or high-fidelity, incorporating more detail. They are essential for ensuring that the user experience is intuitive and that all necessary features are included before moving on to the more detailed design phase.