[rmolnav]

Does anybody know what gravity actually is? 

In my last post, as usually, I didn´t consider that question ("whatever the deep explanation of gravity").
I think we should be able to clearly understand WHAT actually happens, before trying to understand WHY it happens, in the sense of the deep "nature" of gravity.
By the way, what I said about our way of feeling gravity, may also be said for objects ... They don´t feel as we do, but different internal stresses occur across them, and subsequently they get deformed differently, depending on same factors: forces which prevent them (as a hole or affecting its different parts) to get the required gravity acceleration ... That´s what they "feel", not gravity itself. Their answer to ONLY gravity would be, as ours, just to accelerate with local "g" ...

[Bill S]

Does anybody know what gravity actually is? 

I think not, I certainly don't, but here's a thought that might be worth looking at, on its way to the recycle bin.

A body of the mass and density of the sun, for example, will cause relatively gentle curvature of spacetime, over a large area.  If this mass were compressed to the size of the Earth, the curvature of spacetime around it would be much more severe. 

In terms of the rubber sheet model, the depression in the sheet becomes deeper, and steeper sided, either as a result of an increase of the mass within it, or as a result of the compression of that mass. 

Given a situation in which an enormous mass, such as the total mass of the Universe, is compressed into an unthinkably small “speck”, with a diameter no greater than the Planck distance, we might just be forgiven for referring to the resulting curvature of spacetime as “infinite”.   In fact, scientists often do just that.  This, we are told, approximates to the state of the Universe at the instant of the Big Bang.
 
 If this is the case, it follows that every particle of matter and all the energy in the Universe, at the start of its life – or of this cycle of its life – occupied the same point in spacetime.  The energy, whatever its source, that caused this infinitesimal, primordial speck to expand, transforming itself into billions of light years of spacetime, matter and energy would also have caused the curvature of spacetime to expand, and to “soften”, but, it would always remain curved, thus it would always tend to return to its original condition, like a rock, that has been picked up, falling back to Earth once the restraining force has been removed.
 
This would mean that the energy which drives gravitational attraction is the potential energy imparted to every particle in the Universe by the Big Bang. 



 

[rmolnav]

Does anybody know what gravity actually is? 
As example, in my classes at Netfilx University    I see that the moon is racing around the dent in the fabric of space which is being created by the mass of the Earth, or so I vaguely maybe understand it.   
What force is causing the Earth to create this dent in the fabric of space?

Perhaps it would interest you to have a look at:
https://www.thenakedscientists.com/forum/index.php?topic=71799.msg527540#msg527540
where we are discussing, not the actual, deep nature of gravity, but the steps which supposedly lead Einstein to look for something "out of the box" …
A statement that doesn´t make things any easier to understand, as what you quoted, could be:
"… the reason things are going to drop when I trow them, is because there´s a force attracting us down to the center of the earth … relativity tells you that´s not the right way to think … What´s really going on is that YOUR NATURAL PATH (??) in space-time would take you to the center of the earth"