Final answer:
Virtual images, seen in plane mirrors, appear to be behind the mirror but cannot be projected onto a screen. They are the result of light rays reflecting off the mirror, with the angles making them appear as if they are at a specific location behind the mirror.
Step-by-step explanation:
The images you see in a plane mirror are called virtual images because they cannot be projected onto a screen. Unlike real images, virtual images result from light rays that appear to come from behind the mirror but do not actually exist at the location they seem to be. When we observe a virtual image, it appears to be at the same distance behind the mirror as the actual object is in front of it due to the law of reflection, which states that the angle of incidence equals the angle of reflection. Therefore, virtual images seem real, and they can even be photographed, despite not being a tangible presence behind the mirror.