Polycyclic aromatic hydrocarbons (PAHs) constitute a significant group of persistent organic pollutants to environmental and human health. PAHs are a family of chemicals with a wide range of natural and anthropogenic origins (i.e., fossil fuel combustion, industrial emissions, and wildfires) that are defined by their hydrophobicity, poor water solubility, and highly binding organic matter. The characteristics enhance their extensive dispersion in air, water and soil and cause their persistence in the environment. Atmospheric transport, deposition and adsorption to particulate matter and sediments operate to regulate the environmental fate of PAHs. Although the degradation of PAHs is enhanced with the involvement of photochemistry, chemicals, and microbes, the high-molecular-weight PAHs are highly resistant to any breakdown leading to persistent contamination. PAHs remain of primary concern to both ecological and human health because of their toxicity, potential to cause cancer and bio accumulative nature. This chapter focuses on the physical, chemical, and biological character of PAHs and their significance to the environment with the emphasis on the necessity of sophisticated remediation and monitoring solutions that could control the effects of PAHs.