User experience research informs design decisions by providing insights into user behavior, needs, and pain points. This research involves methods like surveys, interviews, and usability testing to gather qualitative and quantitative data. By understanding how users interact with a product, designers can make informed choices on interface design, functionality, and overall experience. The feedback gained through user research helps identify areas for improvement, informing iterations and ensuring the final product aligns with user expectations. Ultimately, this research-driven approach enhances usability and satisfaction.