Subtitles have long been an indispensable part of videos, films, educational courses, and social media content. Yet many still wonder: “What does a subtitle do?” In fact, subtitles are more than just the textual representation of spoken content. They enhance information accessibility, assist hearing-impaired and non-native audiences in understanding content, improve viewing experiences, and play a vital role in cross-language communication and global dissemination. This article systematically introduces the definition, functions, types, and application scenarios of subtitles. Combined with Easysub’s professional solutions, it will reveal the true value of subtitles.