This study presents a comprehensive sociological analysis of the impact of social media on youth behavior, identity formation, and social relationships by synthesizing interdisciplinary theory, empirical research, and contemporary digital scholarship. It conceptualizes social media not as a deterministic technological force but as a socially embedded environment whose influence is shaped by cultural context, institutional structures, individual dispositions, and patterns of use. Through a critical integration of established sociological perspectives and recent evidence, the article examines how digital platforms simultaneously enable social connectivity, self-expression, learning, and civic participation while also generating risks such as mental health strain, cyberbullying, social comparison, distorted self-perception, and diminished face-to-face interaction. Particular attention is given to the ways online engagement restructures peer relations, family dynamics, emotional experience, and normative expectations among youth. By situating digital practices within broader social systems, the study advances a multidimensional analytical framework for understanding youth digital behavior and highlights the complex interplay between technological affordances and social environments. The article concludes with theoretically informed and evidence-based recommendations for educators, policymakers, families, and institutions aimed at fostering balanced, responsible, and developmentally supportive digital engagement.