<p>This study examines the motivations underlying the use of the instant messaging (IM) application LINE through the lens of uses and gratifications theory (UGT). By categorizing users based on demographic and personal characteristics, the research utilizes latent class analysis on data from the 2018 Taiwan Communication Survey (<i>N</i> = 2,028) to identify four distinct user groups: non-users, relationship maintainers, omnivores, and social groomers. Non-users, typically older and exhibiting lower levels of bridging social capital, contrast sharply with users, who display a range of engagement levels and varied gratificational needs. In particular, social groomers utilize LINE to alleviate feelings of disconnection from family and friends, much like individuals experiencing fear of missing out (FoMo). These users also report significantly lower levels of loneliness and increased bridging social capital. The findings indicate that while age is correlated with the use of instant messaging apps, it is primarily the users’ needs and purposes that shape their communication habits. This research enhances the existing literature by elucidating the background factors that influence distinct uses, gratifications, and intentions regarding IM app utilization, offering valuable theoretical and practical insights for academic discussions and the development of communication technologies.</p>