What is the difference between an ordinary visit to graves and visiting shrines to which journeys are undertaken, such as the shrine of Hussein, may God be pleased with him?

Legitimate visitation of graves differs from innovative visitation. Legitimate visitation is for remembering the Afterlife and supplicating for the deceased, and it is a form of kindness to the dead. As for innovative visitation, it involves supplicating to the dead and seeking needs from them, or swearing by them in the name of Allah, or believing that supplication near their graves is superior. This is among the causes of shirk (polytheism) and the introduction of a religion not sanctioned by Allah. The Imams of the Muslims have forbidden this innovative visitation, which was not practiced by the Companions or the Successors. As for setting out on a journey (شد الرحال) specifically to visit graves, the preponderant opinion is that it is generally prohibited, whether for the graves of prophets and righteous individuals or for common people. However, it is permissible to supplicate for the deceased, seek forgiveness for them, give charity on their behalf, and visit their grave if it is nearby, without undertaking a special journey for it.