The study systematically identifies and characterizes new anti-phage defense systems in microbial genomes. By analyzing gene families clustered near known defense genes, the researchers identified 277 candidate families, from which 41 were selected for further analysis. These candidate systems were validated in model bacteria, *Escherichia coli* and *Bacillus subtilis*, and nine previously unknown anti-phage and one anti-plasmid defense systems were discovered. These systems, including the Zorya, Thoeris, and Druantia systems, exhibit diverse mechanisms of action, such as targeting specific phage families or interfering with plasmid transformation. The study also highlights the presence of defense systems in archaea and the potential for these systems to serve as molecular tools in biotechnology and genomics. The findings expand the known arsenal of prokaryotic defense mechanisms and provide insights into the evolution of innate immunity across different domains of life.The study systematically identifies and characterizes new anti-phage defense systems in microbial genomes. By analyzing gene families clustered near known defense genes, the researchers identified 277 candidate families, from which 41 were selected for further analysis. These candidate systems were validated in model bacteria, *Escherichia coli* and *Bacillus subtilis*, and nine previously unknown anti-phage and one anti-plasmid defense systems were discovered. These systems, including the Zorya, Thoeris, and Druantia systems, exhibit diverse mechanisms of action, such as targeting specific phage families or interfering with plasmid transformation. The study also highlights the presence of defense systems in archaea and the potential for these systems to serve as molecular tools in biotechnology and genomics. The findings expand the known arsenal of prokaryotic defense mechanisms and provide insights into the evolution of innate immunity across different domains of life.