CRISPR is an acronym for a bacterial immune system first described in 1987. Since then it has been used to modify human cells and has promise for removing disease causing genes. The below video is an excellent summary of the technique, its many applications and some precautionary words about ethical implications and possible misuse. If you are interested in the subject, the link will lead you to many more detailed and lengthy explanations. The second link is a Wikipedia explanation with some history of the progress of CRISPR.
What is CRISPR?
Genome Editing with CRISPR-Cas9