Salicylic acid (SA) is a plant hormone with a long history in human medicine, used as a herbal remedy and as a defense hormone in plants against pathogens and abiotic stresses. Over the past 30 years, research has revealed SA's complex roles in plant immunity, including its involvement in systemic acquired resistance (SAR), a defense mechanism that protects plants against a wide range of pathogens. SA is synthesized locally and systemically, and its perception involves multiple cellular targets, including metabolic enzymes, redox regulators, transcription cofactors, and an RNA-binding protein. SA also influences post-translational modifications of downstream signaling components and promotes the formation of biomolecular condensates that function as cellular signaling hubs. SA interacts with other plant hormones, such as jasmonic acid (JA), through complex crosstalk, which can be synergistic or antagonistic, depending on the context. SA's role in immunity is further regulated by the NPR family of receptors, which act as transcriptional cofactors and substrate adaptors for ubiquitin ligases. These receptors influence the activity and stability of other transcriptional activators and corepressors, extending their regulatory reach beyond SA responses. Future research aims to uncover the mechanisms by which SA is synthesized, perceived, and regulated in different plant species, as well as how it interacts with other hormones to modulate plant immunity and development. Understanding these processes could lead to new strategies for improving plant resistance to pathogens and enhancing crop yields.Salicylic acid (SA) is a plant hormone with a long history in human medicine, used as a herbal remedy and as a defense hormone in plants against pathogens and abiotic stresses. Over the past 30 years, research has revealed SA's complex roles in plant immunity, including its involvement in systemic acquired resistance (SAR), a defense mechanism that protects plants against a wide range of pathogens. SA is synthesized locally and systemically, and its perception involves multiple cellular targets, including metabolic enzymes, redox regulators, transcription cofactors, and an RNA-binding protein. SA also influences post-translational modifications of downstream signaling components and promotes the formation of biomolecular condensates that function as cellular signaling hubs. SA interacts with other plant hormones, such as jasmonic acid (JA), through complex crosstalk, which can be synergistic or antagonistic, depending on the context. SA's role in immunity is further regulated by the NPR family of receptors, which act as transcriptional cofactors and substrate adaptors for ubiquitin ligases. These receptors influence the activity and stability of other transcriptional activators and corepressors, extending their regulatory reach beyond SA responses. Future research aims to uncover the mechanisms by which SA is synthesized, perceived, and regulated in different plant species, as well as how it interacts with other hormones to modulate plant immunity and development. Understanding these processes could lead to new strategies for improving plant resistance to pathogens and enhancing crop yields.