Emerging pollutants include a diverse array of chemicals and materials, which are becoming of increasing concern due to their potential threats to the human health and environment. Pharmaceuticals, endocrine-disrupting chemicals, pesticides, personal care products, industrial chemicals, heavy metals, nanomaterials, and microplastics are some of the substances often not captured by traditional monitoring approaches. This book chapter details the comprehensive classification of emerging pollutants, including the source, environmental behaviour, and pathway of these pollutants. It investigates into physicochemical characteristics, notably toxicity, bioaccumulation, persistence, and interaction with biological systems, respectively. Further underlines why such interdisciplinary research and technological innovation are necessary to mitigate these risks by integrating insights in terms of analytical techniques and challenges posed by regulatory requirements.