What is hair?

If you're anything like me, most of your thinking about hair is probably directed towards either keeping it or regrowing it, very little is spent wondering about what hair actually is!

Perhaps this isn't too surprising - after all, very few of us want to keep our hair for any reason other than our looks - put simply, we think we look better with it than without. Before we start to look in any detail at the various treatments and regimes out there, though, it pays to take a closer look at hair itself. Only then do we stand a chance of separating those treatments which might be worth paying for from those which are just going to empty our bank accounts.

OK, here's the science bit. Hair is mainly made out of a substance called Keratin, a protein (proteins are linear chains of amino acids). Hair is found only on mammals, and in non-human mammals it is called "fur". In humans there are three distinct types of hair (and remember, we're not just talking about head hair):

Lanugo - a fine hair which covers fetuses

Vellus - body hair often described as "peach fuzz"

Terminal - hair that is longer and thicker than vellus hair

So far, so simple. However things get more complex when we look at hair texture, which is is determined by the diameter of individual hairs and of which there are four main categories: fine, medium, coarse and wiry. Within these textures hair can be categorised yet further according to its density and whether it is straight, curly or wavy - straightness or curliness being determined by follicle shape and the direction the hair strand grows from the follicle.

We've looked at what hair is made of (a protein called Keratin) and how we describe it once it's grown, tomorrow we'll look at how hair grows.