What is a commonly used tool to visualize UI/UX design?

Wireframes are a fundamental tool in the visualization of UI/UX design. They serve as low-fidelity representations of a website or application's layout, focusing on the structure and functionality rather than the final visuals. This allows designers to outline the essential elements of the interface, such as navigation, content areas, and interactivity, without being distracted by specifics like colors or font choices.

Creating wireframes is a crucial step in the design process because it helps stakeholders, including clients and team members, understand the design's requirements and flow before investing time and resources into higher-fidelity prototypes or development. The simplicity of wireframes enables rapid iteration based on feedback, ensuring that the UI/UX aligns with user needs and expectations early in the design process.

The other tools listed, while useful in various contexts, do not specifically focus on the visualization of UI/UX design. Data Flow Diagrams illustrate how data moves through a system, flowcharts detail processes or workflows, and Gantt Charts manage project timelines. Each of these has its place in project management or system analysis, but none serve the particular purpose of crafting a visual representation of user interface design as effectively as wireframes do.