In Hindu philosophy, a Yuga refers to an age or era within a cycle of time. There are four main Yugas: Satya Yuga, Treta Yuga, Dvapara Yuga, and Kali Yuga. Each Yuga represents a decline in virtue, morality, and human lifespan, with Satya Yuga being the golden age of truth and righteousness, while Kali Yuga is characterized by strife and ignorance. The cycle of Yugas is believed to repeat over vast periods, with each cycle lasting millions of years. The current age, Kali Yuga, is said to have begun around 5,000 years ago and is expected to last for approximately 432,000 years. Understanding Yugas helps in grasping the cyclical nature of time in Hindu cosmology.