Interferons (IFNs) are a family of proteins with broad antiviral and immunomodulatory effects, playing a key role in biomedicine. Since their discovery in 1957, IFNs have been studied extensively, leading to a deeper understanding of their mechanisms in cellular signaling, gene transcription, and immune responses. They are now recognized as prototypic biological response modifiers, effective in treating viral infections, cancer, and multiple sclerosis (MS). Recent advances in molecular biology have enabled the development of new therapeutic strategies targeting IFN production through Toll-like receptors (TLRs), leading to more effective treatments. IFNs are produced in response to viral or microbial stimuli, triggering signaling pathways that lead to the expression of IFN-stimulated genes (ISGs), which mediate antiviral, antitumor, and immunomodulatory effects. The signaling pathways involve TLRs, such as TLR3, TLR7, TLR8, and TLR9, which recognize viral nucleic acids and activate downstream signaling cascades. These pathways lead to the activation of transcription factors like IRF3, IRF7, and NF-κB, which regulate the expression of ISGs. The IFN system includes several types, such as type I (IFN-α, IFN-β, IFN-ω, IFN-ε, IFN-κ), type II (IFN-γ), and type III (IFN-λ). Each type has distinct receptors and signaling pathways, contributing to diverse biological functions. ISGs, such as OAS, RNASEL, PKR, and IFIT, play critical roles in antiviral defense by inhibiting viral replication, promoting apoptosis, and modulating immune responses. IFNs have been used in clinical settings for treating viral infections, cancer, and MS. However, their use has been limited by side effects and the need for more targeted therapies. Recent research has focused on developing small-molecule activators of ISGs and TLR agonists to enhance IFN activity. These approaches aim to improve the efficacy and safety of IFN-based therapies. In summary, IFNs are essential in biomedicine, with ongoing research aimed at understanding their mechanisms and developing new therapeutic strategies. Their role in innate and adaptive immunity, antiviral effects, and cancer treatment continues to be a focus of scientific investigation.Interferons (IFNs) are a family of proteins with broad antiviral and immunomodulatory effects, playing a key role in biomedicine. Since their discovery in 1957, IFNs have been studied extensively, leading to a deeper understanding of their mechanisms in cellular signaling, gene transcription, and immune responses. They are now recognized as prototypic biological response modifiers, effective in treating viral infections, cancer, and multiple sclerosis (MS). Recent advances in molecular biology have enabled the development of new therapeutic strategies targeting IFN production through Toll-like receptors (TLRs), leading to more effective treatments. IFNs are produced in response to viral or microbial stimuli, triggering signaling pathways that lead to the expression of IFN-stimulated genes (ISGs), which mediate antiviral, antitumor, and immunomodulatory effects. The signaling pathways involve TLRs, such as TLR3, TLR7, TLR8, and TLR9, which recognize viral nucleic acids and activate downstream signaling cascades. These pathways lead to the activation of transcription factors like IRF3, IRF7, and NF-κB, which regulate the expression of ISGs. The IFN system includes several types, such as type I (IFN-α, IFN-β, IFN-ω, IFN-ε, IFN-κ), type II (IFN-γ), and type III (IFN-λ). Each type has distinct receptors and signaling pathways, contributing to diverse biological functions. ISGs, such as OAS, RNASEL, PKR, and IFIT, play critical roles in antiviral defense by inhibiting viral replication, promoting apoptosis, and modulating immune responses. IFNs have been used in clinical settings for treating viral infections, cancer, and MS. However, their use has been limited by side effects and the need for more targeted therapies. Recent research has focused on developing small-molecule activators of ISGs and TLR agonists to enhance IFN activity. These approaches aim to improve the efficacy and safety of IFN-based therapies. In summary, IFNs are essential in biomedicine, with ongoing research aimed at understanding their mechanisms and developing new therapeutic strategies. Their role in innate and adaptive immunity, antiviral effects, and cancer treatment continues to be a focus of scientific investigation.