The term "underline" refers to a typographical feature where a line is drawn beneath a word or phrase to emphasize its importance. This technique is commonly used in written documents, such as essays or reports, to highlight key points or titles. In digital formats, underlining can also indicate hyperlinks, guiding users to additional information. In addition to its visual function, underlining can serve as a tool for organization in note-taking. By underlining important concepts, such as those found in textbooks or lecture notes, students can easily identify and review critical information. This practice aids in comprehension and retention of material.