<p>This review examines recent research on the antibacterial properties of clays, focusing on the mechanisms involved before and after chemical modification that enhance their effectiveness against various Gram-positive and Gram-negative bacteria, both sensitive and resistant. Clays are a cost-effective, multi-mechanism antimicrobial due to their abundance in nature and their key properties. Their high surface area promotes microbial adsorption and contaminant neutralization, their cation exchange capacity makes them a potential sustained-release reservoir for bioactive ions that can produce reactive oxygen species through oxidative stress, and their unique structural properties give rise to specific interactions with the surrounding environment. The review explains these inherent properties of clays in their most general sense, including iron redox chemistry, natural and synthetic impurities, and leachable metal ions, and how they contribute to antibacterial activity. It also covers different modification strategies that strengthen or change natural mechanisms, while critically addressing related challenges and unpredictability. The various antibacterial properties of clays discussed here for therapeutic uses suggest wider potential applications in medical, environmental, and industrial fields such as medical coatings, wound dressings, and water purification.</p>