Antimicrobial resistance (AMR) has emerged as one of the most pressing challenges in modern medicine, threatening the efficacy of treatments and the control of infectious diseases worldwide. While the direct consequences of AMR—such as treatment failure and increased mortality—are well recognized, its broader impact on microbial virulence, community dynamics, and disease spread is only beginning to be understood. This chapter explores the different ways in which resistance mechanisms intersect with microbial metabolism, host interactions, and ecological pressures, revealing a complex landscape where AMR not only enables survival but also reshapes pathogenic potential.