Have you ever wondered what the most reputed scientific article is? Have you ever been curious to know the most essential protein in metabolic reactions? Do you have a burning desire to know which companies concentrate most of the corporate decisions in the world? These questions are all related to the concept of 'centrality' in networks. This talk's aim is to introduce the concept by explaining the famous PageRank algorithm that gave Google the edge over its competitors in the dawn of the 21st century.