Antimicrobial resistance is one of the most important challenges in microbiology and modern medicine. It refers to the ability of bacteria to survive or grow in the presence of an antibiotic that was previously capable of inhibiting or killing them. Resistance may result from genetic changes occurring within bacteria or from the acquisition of resistance genes from other microorganisms. Bacteria have the ability to exchange genetic material, and plasmids and certain mobile genetic elements can contribute to the transfer of resistance traits between cells. The mechanisms of resistance vary depending on the type of antibiotic and the bacterial species. A bacterial cell may produce enzymes that modify or destroy the antibiotic, alter the target site to which the antibiotic binds inside the cell, reduce antibiotic entry across membranes, or use membrane pumps to expel the compound from the cell. Biofilms can also contribute to the increased ability of bacterial communities to tolerate environmental conditions and certain antimicrobial agents. Resistance becomes particularly important when bacteria possess more than one resistance mechanism simultaneously, which may lead to the emergence of multidrug-resistant strains. Microbiology laboratories rely on antimicrobial susceptibility testing to determine the response of bacteria to different drugs. One of the most widely used laboratory methods is the disk diffusion test on culture media, in addition to other methods used to determine the minimum inhibitory concentration (MIC) of an antibiotic. These tests help guide appropriate treatment and reduce the unnecessary use of antibiotics. The study of antimicrobial resistance is not limited to the medical field; it also encompasses the environment, hospitals, food, water, and animals, because resistance genes can be transferred among different microbial communities. Therefore, this topic represents an important intersection of microbiology, genetics, medicine, and public health