CRISPR Associated Proteins are enzymes that associate with CRISPR RNAs to bind to, and alter DNA or RNA target sequences.
Cas enzymes originate in bacteria and as such a wide variety of types exist. Some are used for genome editing or editing RNA. There are also verions that have been altered in the lab to perform specific tasks.
Common examples include Cas9 which makes a double-stranded break in a target DNA sequence, and Cas13 which targets RNA.