Explore the second session of special and general relativity taught by Joseph Samuel during Day 3 of the RRI Astronomy Summer School (RASS) 2025. This 1-hour 8-minute lecture is part of a fully funded 2-week workshop combined with an 8-week research internship program hosted at the prestigious Raman Research Institute in India. Designed for undergraduate and master's students, this comprehensive program aims to provide a solid foundation in astronomy and astrophysics through expert lectures and hands-on research projects. Delve into fundamental concepts of relativity as presented by an expert in the field, preparing you for deeper exploration in astronomy-related research.