Most of the photographic evidence people send us is very easy to debunk using one of the known common mis-identifications below. When reviewing paranormal data, please keep these in mind. It's always best to use critical thinking to identify other possibilities!
Our brains will process an image as something we are commonly associated with. Just as we see familar shapes in clouds, people can see faces in material defects in mirrors or any non-uniform surface. In photographs, any arrangement of shapes can be seen as something else due to our precognitive processes. This isn't limited to our visual sense, either. The same psychological process exists for audio (apophenia), which leads to false recognization of EVPs. We cannot trust our senses because our brain stitches together data collected and translates it into something meaningful to us, whether or not that data actually represents it.
Orbs are the most common misunderstood effect in photographs. Orbs are almost always just particles in the air like dust, skin, pollen, bugs, or anything very small. They will show up when you use a flash that is on your camera. The light from the flash reflects directly back into the lens. To avoid these showing up in photographs, try to avoid using flash, or use another source of light that is at a different angle than what you are trying to take a photo of. It is said that spirits will radiate their own light, so the idea of not using a flash is more appealing to capture true paranormal activity.
Orbs will appear circular (sometimes a shape, if it's larger like a bug), and be semi-transparent. The size and opacity are relative to the particle's distance from the camera.
Moisture manifests in a variety of ways in photographs. Sometimes we can see it with our own eyes, and sometimes only the camera can capture it. Moisture is often mistaken for paranormal entities by people not familiar with what it looks like. The photograph shows moisture in the air caused by the breath of the person taking the photo. Because it was dark, the moisture wasn't seen except when captured with a flash. Another culprit is fog. This occurs a lot along the coast, in the mornings, or any other location prone to high water concentration in the air. Especially when using a flash, the light bounces off the water molecules and reflects back into the lens, resulting in glowing "orbs".
In low-lighting situations, the camera has to leave the shutter open for longer periods of time to collect enough light for the photograph. If there is movement in front of the camera during this time, it appears as semi-transparent, "ghostly" images. In this example, it looks like there is a blueish, transparent, human-shaped entity at the end of the hallway. It's actually just someone walking across the door while the camera's shutter was open.`