1 It is a sign of sexiness
Tossing the hair is a sign of attraction and it's one of the most accurate signs that shows interest. If a woman tosses her hair while facing you, there is a great possibility that she thinks that you are attractive.
2 How does it happen
A hair toss or a hair flip has many forms, but in all cases the woman will use one of her hands to move some of her hair backwards from one side so that her ear and a part of her neck become visible for moments.
3 Why does it happen (scientific explanation)
Body language experts say that when a woman gets attracted to a person, she unconsciously feels like showing more of her skin to attract that person. When a woman flips (tosses) her hair, she is unconsciously trying to show some of her skin.
4 How to make sure it's a sign of attraction
The most powerful indicator of attraction is when the hair flip happens more than once. If the woman does that move a few times in the presence of someone then she most probably thinks that they are attractive.
5 The woman can do this move while looking away
If a man is walking beside a woman, she might still do that move without even looking at him. In such a case, the hair tossing will happen on the side where the man is standing. (See What do women find attractive in men?)
6 When the sign happens in a group
If more than one person is present when the sign happens, this shows that the woman is interested in one of the people present.
7 The woman might do that move for another reason
A woman might toss her hair for any reason, such as adjusting her hair, which is why it's better to see the sign more than once before making any assumptions. (See Why do women wear tight clothes?)
8 The absence of this gesture doesn't mean there is no attraction
According to body language experts, the absence of a certain gesture doesn't necessarily mean that the associated emotion is absent as well. A woman might find a man attractive, yet might not send that unconscious signal.