Can you explain Anselm's ontological argument?

Firstly, its named after Anselm of Canterbury and is called an ontological argument because it is intended to demonstrate the existence of something; namely God in this case. Formalised the argument runs something like this:1) God is a being than which no greater could conceivably exist.2) God exists in the mind.3) A being is more perfect if it exists in reality as well as the mind.4) If God exists only in the mind, then we can con conceive of something more perfect than God.5) However, we cannot imagine something more perfect than God.6) Therefore, God exists in the mind and in reality. This is a reductio ad absurdum argument. this is because it shows that to accept the opposite to the given conclusion would be absurd. Since Anselm suggests that any 'fool' can have an idea of God, a perfect being, in their mind, it follows that it would be absurd to suggest that God is not also mind-independent, if God is also taken to be perfect and we accept that mind-independent existence is a necessary feature of a perfect being.
Plenty of objections to be had here. I would ask the student how they would object and, if they had no ideas, would point to potential problems that they could then elucidate further.