The article by Horodecki et al. explores the concept of mixed-state entanglement and distillation, highlighting the distinction between "free" and "bound" entanglement. They demonstrate that any mixed state that can be distilled into a singlet form must violate the partial transposition criterion, as proposed by Peres. This implies the existence of two types of entanglement: "free" entanglement, which can be distilled and used for quantum communication, and "bound" entanglement, which cannot be brought to the singlet form and is thus useful for different purposes. The authors discuss the physical implications of these findings, drawing parallels with thermodynamics where entanglement is analogous to energy, and the distillability condition is akin to the ability to perform useful "informational work." They also explore the connection between partial transposition and time reversal, suggesting that time plays a crucial role in understanding the relationship between entanglement and distillability. Finally, they raise questions about the nonlocality of inseparable states and the nature of entanglement in nature.The article by Horodecki et al. explores the concept of mixed-state entanglement and distillation, highlighting the distinction between "free" and "bound" entanglement. They demonstrate that any mixed state that can be distilled into a singlet form must violate the partial transposition criterion, as proposed by Peres. This implies the existence of two types of entanglement: "free" entanglement, which can be distilled and used for quantum communication, and "bound" entanglement, which cannot be brought to the singlet form and is thus useful for different purposes. The authors discuss the physical implications of these findings, drawing parallels with thermodynamics where entanglement is analogous to energy, and the distillability condition is akin to the ability to perform useful "informational work." They also explore the connection between partial transposition and time reversal, suggesting that time plays a crucial role in understanding the relationship between entanglement and distillability. Finally, they raise questions about the nonlocality of inseparable states and the nature of entanglement in nature.