The article provides an introduction to the theory of entanglement measures, focusing primarily on finite-dimensional two-party systems. It covers various topics including single-copy and asymptotic entanglement manipulation, the entanglement of formation, entanglement cost, distillable entanglement, relative entropic measures, squashed entanglement, log-negativity, robustness monotones, the greatest cross-norm, uniqueness and extremality theorems. The authors discuss the motivation for studying entanglement measures and their implications for quantum information science. They present the basic principles and main results, including useful entanglement monotones and measures, without detailed technical derivations. The article emphasizes the quantification of entanglement and provides a tutorial overview of the subject, aiming to give readers a comprehensive understanding of the field.The article provides an introduction to the theory of entanglement measures, focusing primarily on finite-dimensional two-party systems. It covers various topics including single-copy and asymptotic entanglement manipulation, the entanglement of formation, entanglement cost, distillable entanglement, relative entropic measures, squashed entanglement, log-negativity, robustness monotones, the greatest cross-norm, uniqueness and extremality theorems. The authors discuss the motivation for studying entanglement measures and their implications for quantum information science. They present the basic principles and main results, including useful entanglement monotones and measures, without detailed technical derivations. The article emphasizes the quantification of entanglement and provides a tutorial overview of the subject, aiming to give readers a comprehensive understanding of the field.