To figure out your hair texture, compare it to a standard piece of thread. Medium is about the same size as a piece of thread, fine is thinner, coarse is thicker. The same way that you can have different porosity, density, and curl patterns around your head, you can also have different textures. For example, grey hairs tend to come in coarser.
As mentioned in the density post, the terminology used for density and texture are often confused. Fine and coarse are terms to describe single strands, while thin and thick reference the number of strands in any give area of your head. So your hair can just as easily be thick and fine or thin and coarse.
A strand of hair has 3 parts- the cuticle, cortex, and medulla. If you’d like to really get in-depth on this, please visit sources I linked here. Almost all hair as the cuticle and cortex. That center piece, the medulla, is not found in all hair.
Fine hair is usually a little more fragile by nature and, appropriately, is missing the medulla. This texture is easy to weigh down and therefore may be a better candidate for low-poo than co-wash (or may need to alternate.) Even if you are low porosity, but have fine hair, you may like at least a little bit of protein in your products since it can help provide the extra structure that your hair craves. Think of it like wearing sneakers with a weak ankle instead of flip-flops.
Medium hair may or may not contain the medulla. You may have some characteristics of fine hair and some of coarse, so you’ll just have to experiment on how much your hair can handle. Sorry!
Coarse hair is the strongest because the medulla is in tact, therefore more resistant to breakage or other forms of damage. It can usually handle co-washing more frequently since there is enough heft to the strands to handle the weight of the conditioner. While coarse strands are desirable, they can also be hard to keep moisturized since you need to penetrate the extra layer to truly have your hair feel hydrated. This can be a tricky line for coarse wavies like myself- you want moisture, but don’t want your waves to be weighed down. Unfortunately you’ll just need to experiment to figure out where that line is for what your hair can handle, but it’ll likely handle heavier products than our fine haired counterparts. The upside? It’s easier to retain length because the structure is present to be able to grow the hair longer.
Did I miss anything? Let me know if there’s anything else you want to know about texture!