The CRISPR tool kit for genome editing and beyond.

CRISPR is becoming an indispensable tool in biological research. Once known as the bacterial immune system against invading viruses, the programmable capacity of the Cas9 enzyme is now revolutionizing diverse fields of medical research, biotechnology, and agriculture. CRISPR-Cas9 is no longer just a gene-editing tool; the application areas of catalytically impaired inactive Cas9, including gene regulation, epigenetic editing, chromatin engineering, and imaging, now exceed the gene-editing functionality of WT Cas9. Here, we will present a brief history of gene-editing tools and describe the wide range of CRISPR-based genome-targeting tools. We will conclude with future directions and the broader impact of CRISPR technologies.