What is meant by supererogatory acts of worship (Nawafil)?

Linguistically, nafilah means 'an increase'. Religiously, it refers to everything that exceeds the obligatory (fardh), being a supererogatory act (tatāwwu’) and a sunnah in worship. Allah legislated it to compensate for any deficiency in the obligatory acts, and to draw closer to Him and attain His love. In the Hadith Qudsi, it is stated: "My servant continues to draw near to Me with supererogatory acts until I love him." Furthermore, it is through these supererogatory acts that deficient obligatory deeds will be completed on the Day of Resurrection. The Prophet, peace and blessings be upon him, said: "Look, does My servant have any supererogatory deeds? If he has supererogatory deeds, [Allah] will say: Complete My servant's obligatory deed for him from his supererogatory deeds."