What is CRISPR used for?

Could you please explain what CRISPR is primarily utilized for? I've heard about it in scientific discussions, but I'm still not quite clear on its applications. Could you elaborate on how CRISPR technology is being employed in various fields? I'm particularly interested in its potential uses in medicine and agriculture. Also, could you mention any ethical considerations or challenges that might arise from the widespread use of CRISPR? I'm keen to understand both the benefits and the potential drawbacks of this technology.