The most basic basic answer one could give is that gravity is caused by mass. This is essentially the answer that would have been given in Newton's era.
In 1916 Einstein published his Theory of General Relativity which quickly became (and still is) the best model for gravitation that we have. In Einstein's theory mass and energy are the same thing (consider his famous equation E = mc^2), therefore you might say that gravity is caused by energy (and all mass is energy).
Einstein's theory also offers a geometric picture of gravity; gravity consists of warps and curves in spacetime (caused by the presence of energy) which alter the paths of particles and give the 'illusion' of gravity.
The most in-depth answer currently available is that gravity is caused by the local Poincare invariance of the Laws of Nature. This basically means that you are free to use any coordinate system at any point in space and time and that the laws of nature are the same everywhere. This requirement automatically leads to Einstein's gravity. This is a result from quantum field theory. (Incidentally you can get the other forces of nature, such as the electromagnetic force from similar symmetry considerations).
i dont know where does gravity comes from please help me and give me the answer
It is due to the electrical forces of the atom that do not completely balance out as had previously been thought. Note that the force of gravity is infinitesimal as compared to that of electrical forces. Like charges repel while unlike charge attract. As detailed in my book "The Secret of Gravity" 1997, the average force of attraction between two hydrogen atoms was calculated and shown to be more than enough to account for the force of gravity. Those who have checked my calculations agree, although the exact values are difficult to determine since they have to be averaged over all possible orbits of the two atoms.
Gravity has been around as long as there has been mass. They come together; you can't separate them.
You come up, you come down.
Its mass
The gravity that keeps the planets in orbit is the sun's gravity, which is a product of the sun's mass.
gravity
gravity
The force is gravity.
the mass of the earth exerts gravity on all objects around it
The blade of a gravity knife is contained within the handle of the knife. It requires a spinning motion or gravity for the blade to come out of the handle.
Gravity affects the bounce of a basketball because if there is gravity, the basketball will come back down after it bounces. But if there is no gravity, the basketball will bounce and travel indefinitely upwards and never come back down until a gravitational force pulls the basketball towards it.
Gravity Falls came out the summer of 2014.Season 2 of Gravity Falls is expected to be out on August 1st.
Of those three questions, the only one that makes any sense is the last one. Gravity doesn't come from a place (the "Where" part) or a thing (the "What" part). Gravity is strongly suspected to have come into existence at the time of the Big Bang, along with the other three fundamental forces. If the Theory of Everything people are right, at extremely high energies the forces combine; gravity would probably have been the first to separate out, at about one Planck time after the Big Bang (a "Planck time" is about 5 x 10-44 seconds).