Introducing, the
Virginia Satir's Iceberg Model:

I think the diagram is quite self-explanatory.
Basically, it shows the external and internal self of a person. Usually, we tend to show certain behaviour on the outside and others may think we're out of our minds, or don't understand us. Of course they don't, because their icebergs aren't ours. We only know our own internal self: beliefs, values, fears, past experiences, our thoughts and feelings, how confident we feel about ourselves etc.
When a person is angry, he or she shows it externally, but in fact, there's so much things lying underneath that water surface, that external mask we usually use to cover up the sensitive stuff we have inside us. Hence, anger is not real. The real thing is the person's beliefs, or values, or fears... Maybe anger rose because of loss of direction in life. Maybe anger came up because of confusion or frustration. Maybe anger appeared due to disappointment, feeling upset.
That's why we tend to regret after being angry at someone, especially our loved ones. Because when anger subsides, we think more rationally, and the real us emerge again, with the truth of being lost, being confused or frustrated, being upset or disappointed. These are the underlying feelings of what's shown on the outside.
Going further down into our inner world, we have all those feelings because we believe that the person is someone whom we love, whom we care so much about, that we don't wish for them to get hurt. Yet, this wish wasn't fulfilled.
Humans operate on Love.
We're so different and unique, yet we're all the same.
We all need Love.