Celestial reference frames are one of the fundamental tools in astronomy and space science which offers a structured way to describe the positions and movements of celestial bodies. This document provides a comprehensive overview of several important reference frames: the Geocentric Celestial Reference Frame (GCRF), which aligns with distant stars and is unaffected by Earth's rotation; the Heliocentric Inertial Frame (HIF), centered on the Sun and used for interplanetary missions; the Earth-Centered Earth-Fixed Frame (ECEF), which rotates with the Earth and is used for surface positioning; and the Orbital Frame, including Radial Tangential Normal (RTN) and Hill frames, used for satellite dynamics. Additionally, the Geocentric Ecliptic Coordinate System (GECS) and the Ecliptic Frame are discussed, focusing on their alignment with the ecliptic plane and Earth’s orbit.