Fuente: Citrus Byproducts Extraction This chapter explores the evolution of skincare, tracing its transformation from apothecary formulations to industrial-scale products influenced by petrochemical and pharmaceutical advancements where consumer demand for safety, sustainability, and efficacy is driving new developments. We discuss the impact of environmental stressors such as ultraviolet radiation, urban pollution, and climate variability on the skin’s barrier function and aging, addressing the physiological needs of skin from infancy through adulthood. Data from randomized controlled trials and regulatory programs are used to support discussions on efficacy, tolerability, and formulation optimization highlighting regional differences in ingredient approval and safety data requirements particularly around sunscreens and over-the-counter actives. Biomimetic ingredients are emphasized for their multifunctional role in supporting hydration, skin barrier function, inflammation reduction, and photoprotection. Special attention is given to the rise of biocosmetics with a focus on the therapeutic potential of probiotic, prebiotic, postbiotic, synbiotic, and bacteriophage-based skincare. These biocosmetics offer promising strategies to modulate skin health in infants, children, pregnant women, the elderly, and in people with conditions like acne or eczema. By blending ancient ethnobotanical practices with modern biotechnological insights, we propose that the skin microbiome may be both a tool and a target for innovation in evidence-based skincare. In parallel, microbiome sequencing platforms and artificial intelligence technologies are revolutionizing ingredient and formulation development, enabling highly personalized product design and predictive modeling of efficacy and tolerance. These advances represent a paradigm shift from traditional antimicrobial agents toward biologically derived, targeted modulators of skin homeostasis reflecting the interdisciplinary nature of modern skincare research.