LIghting is a huge component of photography. Duh. But i'm specifically talking about the temperature of lighting.
Our eyes adjust automatically to see true whites in all lighting because our brain does all the work for us. But our cameras can't differentiate on their own. Setting the white balance is the process of removing color casts so that the white you see in person, is rendered white in the actual image.
Have you ever taken a photo inside your house with the lights on and it seems very orange?
Start to pay attention to lights and the coloring they give off. Cloudy days give off more of a blue color than sunny days. Fluorescent light gives off a green hue and incandescent light gives off an orange hue.
Your camera has gotten smarter though. There are white balance settings that will help you achieve better color balance in your images. NIkon and Canon differ a little in what their icons look like and are labeled as, but settings for auto, flash, cloudy, shady, sunlight, and incandescent are standard. Play around taking a picture of the same subject with the different white balance settings and notice the difference.
Extra tip: Don't forget to check the white balance before you shoot! Nothing is worse than capturing that split second moment and then realizing your color balance was set for the opposite of what it should've been. You'll get some pretty gnarly color hues if the white balance is incorrectly set.