According to the hair shaft specifics hair are broken down into five basic sorts: normal, thin, whirly, long and curly:
Normal hair - the hair, which may be medium-thick and heavy, usually they have a healthy shaft structure, shine naturally and well-reflect light. Normal or medium-thick hair has a thickness of 0.0050 to 0.0075 mk. Thick hair has a thickness of 0.0076 to 0.0155 mk. and more. If hair thickness is less than 0.0050 mk. those hair are considered to be thin.
Thin hair - thin hair is not a disease, it is just one of the hair sorts. Thin hair cannot turn into thick, hovewer you can increase their diameter for some time. Thin hair lack the strength and friability because of the small diameter of each hair. Usually, in case of thin hair the scalp skin is sensitive and hair look dim and luterless. Thin hair are very sensitive to mechanical factors and very vulnerable. However hairstyles are easy to create as they are soft, but such a hairstyle does no last long. 
Wirly hair - they are often straight hair, but they grow in vortexes. Such hair disagree with a normal hair cut in their attempt to change direction. Such hair require the right care products and proper cutting and hairstyles.
Long hair - depending on their length had undergo  many procedures (washing, drying, combing, etc.). There are obvious differences between these hair shaft structure at the root and often worn out tip. So it might be necessary to take into account the selection of hair care products and procedures, that might be completely different for the root and tip parts of such a hair.  
Curly hair, in turn, are divided into naturally and chemically curled hair:
- Naturaly curly hair are almost always strong, although there are often dry, and might be even twisted. Such a hair are suitable for any hairstyle which does not require additional drying or twisting, all efforts should be made to dry these hair naturally. Care should be similar to all dry, porous, brittle or damaged hair care.
- Chemically curled hair - lots of men and women who have naturally straight hair, want them to be curly. This is easy to do by means of chemical hair perming and hair for a few months remain curly till they grow out. However, no matter the chemical permanent used was severe or soft,  the chemical damage remains in effect to the hair shaft structure for quite a long time, so such a hair requires  much more care in comparison to chemically untreated hair. Basically after chemical alteration hair keratin sulfur bridge structure becomes fragile and this will require such a special care to be used.
It is important for each type of hair especially in case of problems to choose appropriate care selection.