Gene editing is the process of altering DNA at specific locations in various cell types and organisms. It involves inserting, removing or replacing DNA, which can shut down certain genes, introduce new genetic traits, or fix harmful gene mutations. Because of its simple design, low cost, high efficiency, good repeatability, and quick results, CRISPR-Cas systems have become the most popular tool in molecular biology labs around the world. In this review, I will cover an overview of CRISPR-Cas systems, including their innovations, uses in human diseases research and gene therapy, as well as the challenges and opportunities they face in real-world applications.