Bacteria are under constant threat of invasion by bacteriophage (viruses which infect bacteria). To prevent bacteriophage from entering and overtaking the bacteria, bacteria utilize defense systems to identify and destroy foreign elements. One method of defense is called CRISPR-Cas (Clustered Regularly Interspaced Short Palindromic Repeats - CRISPR-Associated). Many different bacteria and most archaea use CRISPR-Cas systems. There are many diverse types of CRISPR-Cas systems, each of which provides defense in a slightly different way. One such CRISPR-Cas type is called type IV. The type IV CRISPR-Cas system is poorly understood and there are very few studies published on type IV systems. This dissertation details some of the first studies done on type IV systems, showing that some type IV systems are indeed defense systems, while others may have evolved a non-defense function. Several biochemical studies were performed to better understand the underlying mechanisms of type IV systems. Historically, the study of CRISPR-Cas mechanisms has led to innovations in gene editing, cancer research, diagnostics, therapeutics, and much more. The work described here significantly furthers the CRISPR-Cas field and may lead to the discovery of new, impactful mechanisms and biological tools.