Dua is asking Allah for help or for the fulfilment of a particular need. It expresses a slave's helplessness and dependence on Allah, the All-Powerful and Merciful. It is the channel through which one gets directly in touch with one's Creator.
The purpose of man's creation is worship and according to a Hadeeth, 'dua is the essence of worship'. (Tirmizi) And according to another Hadeeth, 'dua is the worship'. (Tirmizi)

One should keep in mind that the acceptance of duas also depends on the expectations of a person. Allah deals with people in accordance with what they expect of Him. In one Hadeeth, the Prophet sallalahu alayhi wasallam has related the following Statement of Allah: 'I treat my servant as he expects of me…' (Bukhãri, Muslim)

This application contains some precious Duas that are useful in attaining knowledge. May Allah give us all the tawfeeq to turn to Him for all our needs and may He fulfill all our lawful needs of this world and the Hereafter. Ameen.