This book is suggested for the researchers who are interested in computer assisted language teaching and learning. It would be a pathway for understanding the difficulty of subtitles from text complexity in listening and reading perspectives. Moreover, it further investigates the difficulty of subtitles through a mixed-method study from students' perspectives. It sheds light on a way to calculate the difficulty of subtitles in videos, with a view to informing pedagogical decision-making about the effective use of subtitles in videos in the classroom.