Why do Hindus Worship Yamraj on Diwali?

Chhoti Diwali is being celebrated in the country today. The festival of Narak Chaturdashi or Chhoti Deepawali is celebrated on the Chaturdashi date of Krishna Paksha of Kartik month. Chhoti Diwali has great importance because this festival, which falls a day before Diwali, is also known as Narak Chaturdashi and Roop Chaturdashi. There is a tradition of worshipping Yamraj on Chhoti Diwali i.e. Narak Chaturdashi. Along with this, Yam's lamp is also lit and what is its importance?