Tropism is plant movement towards or away from a stimulus. A Stimulus is something that causes a response. There are many types of tropism. All forms of tropism can be either positive or negative. Positive tropism is when a plant turns toward a stimulus, and Negative tropism is when plants turn away from a stimulus. A few are listed below:

Phototropism: plant movement in response to sunlight
Example: A plant shifted or bent to face the sun. Plants can also shift themselves to face the sun throughout the sun

Gravitropism: plant movement towards or away from the earth
Example: Downward growth of roots and upward growth of shoots

Thigmotropism: plant movement towards or away from touch
Example: Vines that grow on a surface

Hydrotropism: plant movement towards or away from a water source
Example: A plant growing toward a pond

Tropism

Phototropism

Gravitropism

Thigmotropism

Hydrotropism