The immune system provides organisms with protection against many pathogens to which they are continuously exposed. Its main role is to recognize and eliminate all molecules that might harm the host's health, with the immune response being either innate (non-specific) or adaptive (specific). Innate immune cells are the first line of defense when encountering foreign particles. Consequently, they have many pattern recognition receptors on their surface and within intracellular spaces, which detect molecular patterns associated with pathogens and tissue damage – specific molecules that signal cellular contamination. These receptors are classified into several groups: TLR, CLR, NLR, ALR, RLR and cGAS, and can be membrane-bound or cytoplasmic. Their activity initiates signaling pathways that result in the production of inflammatory mediators, including cytokines and antimicrobial peptides. They also interact with various other molecules, such as adaptor proteins, kinases and transcription factors. Although pattern recognition receptors are an important component of the immune system, it has been observed that their mutations are associated with tumorigenesis and numerous autoimmune diseases. However, due to these characteristics, these cellular sensors enable the development of new, more effective therapies for the treatment of the aforementioned conditions, thus they remain a current topic in scientific research.