In the digital age, social media platforms have emerged as powerful spaces where youth not only interact but also experiment with and construct their identities. This article critically examines the influence of platforms such as Instagram, Tik Tok, Snapchat, and X (formerly Twitter) on youth identity development and explores how these evolving identity practices impact broader social cohesion. Youth today navigate complex networks of digital performance, where identity is shaped by peer feedback, algorithmically curated content, and global cultural flows. While these platforms offer avenues for self-expression, empowerment, and group belonging, they also foster echo chambers, comparison anxiety, identity polarization, and performative behaviors. Furthermore, the role of influencers, viral trends, and platform-specific aesthetics reinforce norms that often privilege superficiality over authenticity. It also investigates the political implications of identity radicalization and ideological polarization that emerge from algorithmic filtering and targeted content delivery. Through case studies from the United States, Iran, Germany, and Nigeria, the article provides empirical grounding to illustrate both the risks and potentials of youth digital engagement. A comparative lens between Global North and Global South contexts highlights the nuances of digital identity formation across sociocultural environments. Finally, the article calls for a multidimensional policy response involving education, media literacy, platform design, and civic engagement initiatives to ensure that social media becomes a tool for inclusive identity development and enhanced social cohesion. The findings underscore the urgent need to understand and address the sociopsychological and political ramifications of digital identity in the lives of young people today.