why does chromatin fibres supercoil during cell division? What is supercoiling?

Dear Student, Supercoiling is the over and under winding which is very important in many biological process. Nucleosome (length of DNA wrapped around histones) fold up to form chromatin fiber which further tightly coiled up to form chromatid. The main purpose of coiling of chromatin is to compact DNA, RNA to prevent DNA damage and gene expression. Thank You!