1. Objects fall to the ground: The most obvious evidence for gravity is that objects fall to the ground when we drop them. This is because gravity pulls objects towards the center of the Earth.

2. Planets orbit the sun: Gravity also keeps the planets in orbit around the sun. The sun's gravity pulls on the planets, causing them to move in a circular path around it.

3. Tides: Gravity also causes the tides. The moon's gravity pulls on the Earth's oceans, causing them to rise and fall.

4. Gravitational waves: Gravity is also responsible for gravitational waves. These are ripples in spacetime that are caused by the acceleration of massive objects. Gravitational waves were first detected in 2015 by the Laser Interferometer Gravitational-Wave Observatory (LIGO).

5. Time dilation: Gravity also causes time dilation. This means that time passes more slowly in a stronger gravitational field. Time dilation has been measured by the Global Positioning System (GPS) and other experiments.

6. Gravitational lensing: Gravity also causes gravitational lensing. This means that light from a distant object can be bent by the gravity of a massive object. Gravitational lensing has been used to study the properties of black holes and other massive objects.

These are just a few of the ways that we know that gravity exists. Gravity is one of the fundamental forces of nature, and it is responsible for holding the universe together.