Supplication expresses a person's relationship with Allah. Turning to Him in difficulty, asking for goodness, and hoping in His mercy are important aspects of duʿāʾ. Its manners include humility, attentiveness, sincerity, and reliance upon Allah.
ادْعُونِي أَسْتَجِبْ لَكُمْ
Call upon Me; I will respond to you. (Qur'an, Ghafir 40:60)
الدُّعَاءُ is not merely wishing for something; it is asking Allah. A person may ask for recovery from illness, guidance, or goodness for others, and thereby acknowledge dependence upon the Creator.
Supplication should involve the heart as well as the tongue. It is a central act of devotion, but worship also includes prayer, fasting, and other forms of obedience.