What are the limits and nature of supplication (du'a), and can the impossible be achieved through it?

Allah has commanded us to supplicate (make du'a) and encouraged us to do so frequently for the good of this world and the Hereafter, as long as it does not involve sin, severing ties of kinship, or transgression. Transgression includes asking for something that is impossible, either religiously or naturally, as this demonstrates ill-manners with Allah. Therefore, transgression in supplication is any request that contradicts Allah's wisdom, His law, or His command, or that implies something contrary to what He has revealed.