After nearly 15 years as CEO, Tim Cook is stepping down from Apple, marking the end of a historic era for the tech giant. Cook, who took over from Steve Jobs in 2011, transformed Apple from a $350 billion company into a nearly $4 trillion powerhouse. Under his leadership, Apple expanded its ecosystem, launched major products, and became one of the most valuable companies in the world. NDTV's Apurva Adhikari reports.