If there's one thing that’s certain about photos on the internet, it’s that nobody sees the same thing as you. In general, most monitors are too bright, and the color profiles vary by manufacturer. As the monitor gets old, the colors tend to change also. It’s more of an issue with older bulb light monitors, and less so with LED, but still, these colors change over time. This tool is especially useful when you use multiple monitors or print your work. 

In this video, Aaron Nace of Phlearn examines the topic of color calibration and why this is an especially important issue for photographers.