A loading spinner is a visual indicator used in user interfaces to show that a process is ongoing. It typically appears as a rotating circle or a series of dots, signaling to users that they need to wait for a task to complete, such as data loading or file processing. This helps manage user expectations and improves the overall experience by providing feedback during potentially long wait times. Loading spinners are commonly found in various applications and websites, including those built with frameworks like React or Angular. They are essential for maintaining user engagement, as they reassure users that the system is working and not frozen, ultimately enhancing usability and satisfaction.