The Introduction sketches the main technological and legal challenges LEAs face in criminal investigations when seeking to collect electronic evidence in the digital era. It gives an overview of the relevant legal framework at EU, Council of Europe and international level, including recent developments such as the e-Evidence Regulation and the Second Additional Protocol to the Cybercrime Convention, and identifies some missing pieces of the puzzle. Next, the chapter explains the main research objectives of this handbook, before presenting its overall structure and introducing the subsequent chapters.