On the day before Holi, also known as Chotti Holi, people light fire with dried leaves and branches. This bonfire commemorates the death of evil Holika.
According to legend, the demon king Hirnakashyipu was fed up with his son Prahlad’s devotion for Lord Vishnu. After numerous failed attempts, the king took the help of his sister Holika who was immune to fire. She sat with young Prahlada in fire but to the surprise of all Prahlad came out unscathed. And Holika was consumed by the fire.
The fire symbolizes the victory of young Prahlad over evil Holika. Young Prahlad, who represents goodness, was able to overcome the evil with his ardent devotion for Lord Vishnu. The bonfire that is lit during Holi represents the victory of good over evil.