1. Completely protective styles
Hide the ends of hair from view. Hair ends are the oldest segment of hair on your head and also the weakest. Hiding them from view can help to reduce breakage.
When your hair is pulled together it's much less vulnerable. Think about it this way: is it easier to break one toothpick or ten bunched up together? The answer is the same for hair.
2. Low manipulation protective styles
May have the ends exposed but they require little day-to-day hair handling. Handling such as combing, blow drying and styling hair is when breakage normally occurs.
When my hair was short I could pull a comb through it with zero resistance. Nowadays tangling is such a big issue for me. Frequently with a twist/braid-out or a roller set you can go two or three days without having to restyle your hair thus giving it a break.
3. My favourite hairstyles are both completely protective and low manipulation.
This category is also great when you are transitioning and still figuring out how to manage your natural hair.
When your hair is plaited in some way it gets a proper break and you completely forget about whether or not it's "growing". Ideally, I want to spend most of next year in braids. My only worry is that I have to comb my hair properly to get it plaited and I don't usually do that; I enjoy far less breakage under a minimal comb regime. Finger combing only turned out to be a bad idea for me.
1. Completely protective
2. Low manipulation
3. Completely protective, low manipulation styles
This is a subcategory of completely protective styling. For most of 2011 my hair was too short to be pinned down so I wore hats and scarves over my head whenever I was outside.
Seriously, I am so obsessed about my hair being covered that one day I walked out the house with it exposed my husband shouted "your hair's not covered" like I was about to drop a baby or something. I had to explain that my ends were hidden so it was okay to walk between the house and the car without a hat.
In summary, the whole aim of protective styling is to reduce opportunities for breakage by keeping hair ends hidden and retaining more hair moisture.
Opportunities for hair breakage increase when hair strands are dry and isolated, i.e. not tied up, when hair ends are exposed to environmental elements (sun, wind, cold) and when you're "handling" your hair. If you are trying to grow long hair consider using protective styling more often.
Protective styles are especially helpful during winter, when it is very hot outside and when the central heating makes a room very dry.