Protective styling is simply put, styling your hair in a manner that protects your strands from the harsh elements of the cold, windy, and icy weather as well as just plain over manipulation that we put our hair through when it isn't in protective styles. What do I mean by this? Well I know for me that it took a long while into my hair care journey before I finally got over having my hands in my hair every 5 seconds. Some go even further and comb and brush their hair every single day to several times a day. The problem with this is that our hair strands are much like fibers. Over manipulation of them will cause them to lose their elasticity, thickness, and strength. Because we are striving for (most of us) long and thick healthy hair we have to be mindful of keeping our hair as healthy as possible for as long as possible.
Any style that keeps you from manipulating your hair for a good length of time while the ends are covered or tucked can be considered a protective style. This can be two strand twists, braids, buns, or even wigs and sew-ins. Earlier in my hair journey I used kinky twists as a protective style quite often.
One school of thought on the issue of protective styling is that "I'd rather wear my hair out and enjoy it rather than keep it put away all the time just to obtain length". I totally understand this and at one point even wrestled with this line of thinking myself. To that I will say, as I find myself saying so often, there is a healthy balance that can be struck. I fully intend to enjoy EVERY stage of my hair growth on the way to my goal length, whatever that is. Having said that I want to actually be able to reach that goal length with healthy hair. My fear for people who only protective style until they reach a desired length is that once that reach said length they won't know how to style it in a manner that promotes health because all they've done is protective style and they will lose the length that hid for so long. (Does that make sense?) In my opinion the right place to be in somewhere in the middle of the two extremes.