Penicillin is a broad class of antibiotics derived from certain fungal sources. It functions by targeting the synthesis of peptidoglycan, a vital structural component of the cell walls of many bacteria. By inhibiting the cross-linking reactions necessary for the formation of this wall, the compound disrupts the structural integrity of the bacterial cell, leading to cell lysis and bacterial death. Due to its efficacy against susceptible bacteria and its role in treating deep and superficial infections, it remains one of the most significant classes of antimicrobials used in modern medicine.