The pull you never notice
What Is Gravity?
Everything with mass pulls on everything else. Earth just pulls hardest.
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Step 1 of 5
Things fall because something pulls them.
Falling is not something an object does. It is something done to it. An apple does not choose to go down. Earth pulls it, with a force strong enough to accelerate it about 10 metres per second faster every second.
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Step 2 of 5
The apple pulls the Earth too.
The pull works both ways, with exactly equal force. Earth just has 10²⁵ times more mass, so its movement is far too small to notice.
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Step 3 of 5
More mass means a stronger pull.
A mountain pulls on you, but so weakly you cannot feel it. Earth is 10 million times more massive than the biggest mountain, so it wins completely.
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Step 4 of 5
Distance matters as much as mass.
Gravity fades with the square of distance. Move twice as far from the centre and the pull drops to a quarter — which is why the Moon is held gently.
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Step 5 of 5
Everything falls at the same rate.
Heavy things are pulled harder, but they also resist speeding up more. The two effects cancel exactly, so a hammer and a feather land together — if there is no air.
An Apollo astronaut actually did this on the Moon in 1971. They landed together.
The short version
Gravity is a mutual pull between every pair of masses — Earth just has enough mass to dominate.
Try it yourself
Drop a book and a sheet of paper. Now put the paper flat on top of the book and drop again. Same fall, because the air is out of the way.