In the 1990's Oprah's hairstylist came up with a system to classify hair that has become the primary hair classification system. It's not a perfect system as hair is complex, but so far this is the best we have. He simply classified hair into four main types, and each type has a subclass. His name is Andre Walker and the classification system he came up with is still in use today. Having a general idea of the characteristics of your hair is important as it can guide you in purchasing hair products and learning different styling techniques to maximize your time and capabilities. If you know your hair type it will make it easier to have discussions with other people in person or on the internet about what you can do to style your hair easier and more effectively. Speaking in terms of "my hair is coarse and wavy" might not come across as clearly as "I have a 2C hair type" as this leaves much less up for interpretation.
Type 1A: This hair is the straightest of the straight. It's very difficult to obtain volume as your hair wants to lie down. Oils from your scalp easily travel up the hair shaft giving this type of hair good shine and a smooth texture. Hair is easy to control but can be difficult to obtain textured hairstyles.
Type 1B: This hair type is very straight but there tends to be more density of hair growth than 1A. This creates a thicker look that has less shine to it. Oils from the scalp still travel easily to the tips of hair but there is more hair to absorb the oil. This gives a sheen and shiny look to hair that doesn't appear greasy. Volume is easier to obtain with products but hair does not naturally have volume.
Type 1C: Hair still grows straight but is thick, coarse, but still has some shine to it naturally. This hair type will have natural volume making it easier to style than other Type 1 hair sub-classes. Hair will naturally grow outwards at short lengths but will begin to fall forward once hair gets long enough. When hair falls flat against scalp, there is no curl.
Type 2A - Hair grows with an extended "S" type pattern giving it a slight wave. Texturized hairstyles are easy to pull off, but it helps if you add texture during haircuts. Hair isn't very coarse so it can be a little heavy, using heavier products can weigh down your hair and make it difficult to get desired volume. Using pre-stylers and a blow dryer can greatly enhance volume without causing frizziness as this hair type has the highest oil content of the Type 2 hair type.
Type 2b - This hair type has a more aggressive "S" shape to it's wave and tends to have little hooks at the ends where the next wave starts to form. The hair is more coarse than 2a and can make this hair type difficult to style and work with when using budget products. Hair will have natural texture to it. Blow drying this type will make it frizzy and is prone to fly-aways. High grade products are required to control and keep this hair type healthy.
Type 2C - The letter "S" can quite literally be seen in this hair type. It looks like a series of half circles chained together going back and forth. Sometimes the curls will spiral around themselves. This hair type is extremely difficult to control and is the most coarse of the Type 2 hair types. In most cases, people with this type of hair will keep their hair short (under 3 inches) because it's difficult to manage beyond that length. Or they allow it to naturally grow and have a natural textured hairstyle. Many people with this hair type will have type 3A in parts of their hair.
Type 3A - Hair has loose curls that grow outwards and away from the scalp. Once hair reaches a certain length the hair will fall down as it's heavy but the curls aren't coiled enough to keep growing up. Thick and coarse, it can be difficult to style this type of hair without a straightener and heavy hold products. Usually needs oils to stay hydrated. Many people with this hair type have a mix of type 3A and 2C hair.
Type 3B - Tightly coiled curls that grow outward. Hair is extremely thick but still has noticeable texture. Hair is often characteristics of people that identify as Bi-racial, Samoan, islander, etc. Dwayne "The Rock" Johnson is an individual with this hair type. Very difficult to style in a comb over or something like that. Usually people with this hair type will keep hair really short because it's difficult to maintain. Growing hair out looks like a loose afro.
Type 4A - Tightly coiled hair that is coarse and wiry. The shape of the hair prevents natural hair oils from the scalp to travel more than two inches up the hair shaft. This makes the hair brittle but thick. Hair grows very densely. You can pull on the ends of it and straighten it out, but it will bounce right back to it's original shape. Highly resistant to any sort of desired styling. Hair grows outward and will stand up on its own, but once hair gets long enough it will begin to droop down.
Type 4b - Hair is in a "Z" shape and can grow upward and outward for many many inches. This hair type is extremely thick, dense, and brittle. This hair type can look 80% less long than it actually is because it's so tightly coiled. You'll see people with this hair type using pick combs to extend and shape their hair to remove knots if they grow their hair out. This hair type has many options when it comes to different hairstyles and lengths.