This review discusses the biology and signaling mechanisms of tumor necrosis factor (TNF). TNF is a pleiotropic cytokine that plays a crucial role in immune responses, inflammation, and cell death. It is primarily produced by macrophages and other cell types, and exists in two forms: membrane-bound (memTNF) and soluble (sTNF). TNF signals through two main receptors, TNF-R1 and TNF-R2, which are involved in various cellular processes, including apoptosis, inflammation, and immune responses. TNF-R1 is constitutively expressed in most tissues, while TNF-R2 is mainly expressed in immune cells. TNF-R1 is the primary mediator of TNF signaling, whereas TNF-R2 plays a more significant role in lymphoid cells. TNF signaling is mediated through a complex network of signaling pathways, including the NF-κB pathway, which is crucial for the transcription of inflammatory genes. The activation of NF-κB involves the degradation of I-κB proteins and the translocation of NF-κB to the nucleus. This process is regulated by the IKK complex, which is activated by various signaling molecules, including TRAF2 and RIP. The activation of NF-κB is essential for the survival and function of immune cells, as well as for the regulation of inflammatory responses. TNF also activates the JNK and p38-MAPK signaling pathways, which are involved in stress responses and apoptosis. These pathways are activated through different mechanisms, including TRAF2-dependent pathways and ROS-mediated pathways. The activation of these pathways can lead to the induction of apoptosis, inflammation, and cell death. In addition to its role in immune responses, TNF has important functions in tissue regeneration and homeostasis. However, excessive TNF activity can lead to pathological conditions, such as septic shock and cachexia. The balance between TNF's pro-inflammatory and anti-inflammatory functions is crucial for maintaining tissue homeostasis. Overall, TNF is a multifaceted cytokine that plays a central role in immune responses, inflammation, and cell death. Understanding the signaling mechanisms of TNF is essential for developing therapeutic strategies for diseases involving TNF dysregulation.This review discusses the biology and signaling mechanisms of tumor necrosis factor (TNF). TNF is a pleiotropic cytokine that plays a crucial role in immune responses, inflammation, and cell death. It is primarily produced by macrophages and other cell types, and exists in two forms: membrane-bound (memTNF) and soluble (sTNF). TNF signals through two main receptors, TNF-R1 and TNF-R2, which are involved in various cellular processes, including apoptosis, inflammation, and immune responses. TNF-R1 is constitutively expressed in most tissues, while TNF-R2 is mainly expressed in immune cells. TNF-R1 is the primary mediator of TNF signaling, whereas TNF-R2 plays a more significant role in lymphoid cells. TNF signaling is mediated through a complex network of signaling pathways, including the NF-κB pathway, which is crucial for the transcription of inflammatory genes. The activation of NF-κB involves the degradation of I-κB proteins and the translocation of NF-κB to the nucleus. This process is regulated by the IKK complex, which is activated by various signaling molecules, including TRAF2 and RIP. The activation of NF-κB is essential for the survival and function of immune cells, as well as for the regulation of inflammatory responses. TNF also activates the JNK and p38-MAPK signaling pathways, which are involved in stress responses and apoptosis. These pathways are activated through different mechanisms, including TRAF2-dependent pathways and ROS-mediated pathways. The activation of these pathways can lead to the induction of apoptosis, inflammation, and cell death. In addition to its role in immune responses, TNF has important functions in tissue regeneration and homeostasis. However, excessive TNF activity can lead to pathological conditions, such as septic shock and cachexia. The balance between TNF's pro-inflammatory and anti-inflammatory functions is crucial for maintaining tissue homeostasis. Overall, TNF is a multifaceted cytokine that plays a central role in immune responses, inflammation, and cell death. Understanding the signaling mechanisms of TNF is essential for developing therapeutic strategies for diseases involving TNF dysregulation.