Human Interleukin-8 (IL-8), also known as CXCL8, is a potent pro-inflammatory chemokine that plays a central role in innate immunity by mediating neutrophil chemotaxis, activation, degranulation, and respiratory burst at sites of infection or tissue injury. Produced by macrophages, monocytes, epithelial cells, endothelial cells, and fibroblasts in response to microbial products and inflammatory cytokines such as IL-1β and TNF-α, IL-8 signals primarily through the G protein–coupled receptors CXCR1 and CXCR2 to drive rapid neutrophil recruitment and amplification of inflammatory cascades. Elevated IL-8 levels are associated with numerous acute and chronic conditions, including sepsis, acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD), asthma, inflammatory bowel disease, rheumatoid arthritis, psoriasis, and multiple cancers where IL-8 contributes to tumor angiogenesis, metastasis, and immune modulation. Dysregulated IL-8 signaling is implicated in cytokine storm syndromes and severe viral infections, including influenza and COVID-19. As both a biomarker and therapeutic target, human IL-8 is central to research on neutrophil-driven inflammation, cancer progression, and immune-mediated tissue injury, with CXCR1/CXCR2 antagonists and pathway inhibitors under investigation for inflammatory and oncologic indications.