Gravity is described by the theory of general relativity, which is a theory of gravitation proposed by Albert Einstein. According to this theory, gravity is not considered as a particle or a wave in the conventional sense. Instead, it is described as the curvature of spacetime caused by mass and energy.
In general relativity, massive objects like planets, stars, and galaxies create a gravitational field that curves the fabric of spacetime around them. Other objects with mass or energy then follow the curved paths dictated by this curvature. This is often visualized as objects being "attracted" to each other, but it is more accurately described as objects following the curvature of spacetime caused by the presence of mass or energy.
While the concept of particles and waves are commonly used in physics to describe the behavior of matter and energy, gravity itself is distinct from these notions. It is a fundamental force of nature that affects all objects with mass or energy. However, it's worth noting that there are particles called "gravitons" hypothesized in some theories of quantum gravity, but their existence has not been experimentally confirmed yet, and they are not part of the currently accepted framework of general relativity.