Photoreceptor cells are specialized cells found in the eyes of animals that are responsible for detecting light and transmitting visual information to the brain. There are several synonyms for photoreceptor cells, including rod cells, cone cells, and retinal photoreceptors. Rod cells are responsible for detecting light in low levels, while cone cells are responsible for color vision and high levels of light. Other types of photoreceptor cells include ganglion cells, which transmit visual information to the brain, and bipolar cells, which connect rod cells and cone cells to ganglion cells. Each type of photoreceptor cell plays a unique role in the process of vision and is essential for our ability to see the world around us.