Accepted Supplication

Dua is an Arabic term which means to 'call out' or to 'summon' or to 'invoke' and in the Islamic terminology, it means a humble prayer by a modest person to a superior. Muslims use this term and call out to Allah (SWT), and Muslims regard this as one of the greatest acts of worship in Islam.
Supplication definition and meaning in Islam: Supplication is petitioning Allah (SWT) for fulfillment of ones legitimate desires. It is therefore necessary that the supplicant should be conversant with the meaning of the prayer and the etiquette of reciting the prayer. He must recite the supplication with dedication of heart and his attitude should be equally submissive if not more than what he adopts for asking a favor from a fellow human being.
The Holy Prophet of Islam (saw) has said: "Shall I introduce to you a weapon which will protect you both from the evils of enemies and increase your sustenance? They said: Yes, O Messenger of Allah. The Holy Prophet of Islam (saw) replied: Call your Lord day and night, for "Dua" is the weapon of a believer."