This chapter will broadly cover the newest genome editing technology, clustered regularly interspaced short palindromic repeats (CRISPR), and CRISPR-associated system (Cas), as a critical tool for a modern research laboratory. Multiplex gene mutagenesis, tissue-specific gene disruption, DNA insertions, transcriptional activation, transcriptional repression, megabase-sized deletions, translocations, and genetic screens are all possible with CRISPR/Cas technology. How CRISPR-genome editing works, its applications, and considerations for best use will be discussed.