Sri Narasimha Chaturdasi is the appearance day of Lord Narasimhadeva, the half man and half lion form of the Lord. Lord Narasimhadeva is an incarnation of Lord Krishna, the Supreme Personality of Godhead.
Prahlada Maraharaja was a great servant of Krishna, because of this Prahlada’s father wanted to kill him. Lord Krishna then appeared in the form of a half man half lion to save Prahlada from the attacks of his demoniac father. Lord Narasimhadeva’s incarnation teaches us that Lord Krishna always protects His servants.