Innate immunity serves as the body's first line of defense against invading pathogens, providing a rapid and nonspecific response to potential threats. This crucial component of the immune system is present from birth and does not rely on prior exposure to specific pathogens. The skin and mucous membranes act as physical barriers, preventing the entry of microbes into the body. Additionally, various antimicrobial substances, such as enzymes and peptides, are present in bodily fluids, further inhibiting the growth and spread of pathogens. Phagocytic cells, including neutrophils and macrophages, play a pivotal role in innate immunity by engulfing and digesting foreign particles. These cells recognize common features shared by a broad range of pathogens, allowing for a swift response to infection. The complement system, consisting of proteins in the blood, enhances the immune response by promoting phagocytosis, triggering inflammation, and forming membrane attack complexes that can directly lyse pathogens. This system acts in coordination with other components of innate immunity to amplify the overall defense mechanisms. Innate immunity also includes natural killer (NK) cells, which target and destroy infected or abnormal cells, particularly those with altered surface markers. These cells contribute to the elimination of virus-infected cells and play a vital role in cancer surveillance. While innate immunity provides immediate protection, it also influences the adaptive immune response by signaling and activating specific immune cells. This collaboration ensures a comprehensive and effective defense against a wide range of pathogens, ultimately safeguarding the body from potential threats.