Tropisms are usually named for the stimulus involved (for example, a phototropism is a reaction to sunlight) and may be either positive (towards the stimulus) or negative (away from the stimulus). Tropisms occur in four sequential steps. First, there is a perception to a stimulus, which is usually beneficiary to the plant.
Tropism is a descriptive reaction of a certain stimuli on how an organism responds to the confronted stimuli which can be called positive tropism or negative tropism. In positive tropism as the proposed answer toward involves the organism leaning forward or direct to the acting stimuli whereas the negative tropism is exactly the opposite.
What Is Phototropism? The phenomenon you are witnessing is called phototropism. For a hint on what this word means, note that the prefix "photo" means "light," and the suffix "tropism" means "turning." So, phototropism is when plants turn or bend toward light.