CRISPR-Cas 9 is a system that enables geneticists and medical researchers to edit parts of a genome by removing, adding or altering sections of the DNA sequence. Cas9 is a protein that is programmed by small RNAs to cleave DNA at the DNA strand where a scientist wants it to cut. The Cas9 is complexed with both a crRNA and a separate trans-activating crRNA in order to achieve the site-specific DNA recognition and cleavage. From this scientist can change the genes in the genome of a cell by introducing new genes into the sequence. CRISPR-Cas9 was discovered in adaptive immunity in select bacteria and archaea that enabled the organisms to respond to and eliminate invading genetic material.
This system or technology is better than other biotechnology since it is more accurate and is less likely to result in an error. The reason this is more accurate is it targets the specific spot in the sequence where the new genes need to be added. This is different than the other method of using chemicals or radiation to cause mutations. By using chemicals or radiation you were affecting the entire genome and could get a mutation you didn’t want since it was up to chance. Currently the CRISPR-Cas9 system is the fastest, cheapest and most reliable system for editing genes.
For more information on this you can go to https://www.yourgenome.org/facts/what-is-crispr-cas9 which simplifies the process. For a more in-depth look into it you can go to https://www.neb.com/tools-and-resources/feature-articles/crispr-cas9-and-targeted-genome-editing-a-new-era-in-molecular-biology which goes into the biology of it and explains all the types of RNA that are used in the system.