Please, I just want to ask about supplication (Du'a) and its importance?

Linguistically, supplication (du'a) is a request, and Islamically, it is the turning of a servant to his Lord concerning what he needs for the rectification of his religion and his worldly affairs. Allah has commanded His servants to supplicate for their worldly needs and to lighten their burdens, because it is the only path to their requests, as evidenced by the verses: "And when My servants ask you concerning Me, then indeed I am near. I respond to the invocation of the supplicant when he invokes Me" and "Call upon your Lord humbly and secretly." The supplication of the supplicant is answered as long as he does not hasten or supplicate for sin or the cutting off of ties of kinship. Among the reasons for the answering of supplication are righteousness towards parents, sincerity with Allah, and refraining from what He has forbidden, as in the story of the Companions of the Cave. Man is poor and in need of Allah's mercy and kindness, and rectifying his relationship with Allah prepares him to receive divine aid: "So whoever hopes for the meeting with his Lord, let him work righteousness and not associate anyone with the worship of his Lord."