Explore the brain's perception of self, from trillions of cells forming a single identity to how psychedelics, trauma, synchronized movements, and military formations shape our sense of self. Delve into the fluidity of identity, how external factors like drugs and disorders impact it, and how disruptions in brain networks affect our physical self and location. Discover how the brain extends the boundaries of self to include external objects and tools, expanding the concept of identity. Learn how synchronization in activities like religious rituals and group events forms a sense of unity and belonging.