Did you catch someone looking at you from across the room? In normal social contact, people don't usually hold each other's gaze for more than a second, according to the Social Issues Research Centre. Any more than that generally signals either attraction or confrontation. If someone looks away and then back at you again, that is strong evidence that she is flirting. Add in a smile or an eyebrow raise, and you might as well go over and start chatting.

Watch to see whether the other person moves into your personal or intimate zone to gauge whether he is flirting. According to the Social Issues Research Centre, standing within 4 feet of someone indicates a personal connection and within 18 inches a more intimate relationship. If someone moves into your personal or intimate space, that is a good indication he is flirting. If he is also leaning in with his body turned toward yours, these are signs that he is interested and wants to talk more.

Touch plays an important role in nonverbal flirting. A man might touch you briefly on the arm or playfully admire a bracelet as an excuse to have contact. He may also touch his own face or rub his chin if he is interested in you, according to Jeff Thompson, a communication and conflict specialist in his "Psychology Today" article "Are Man and Woman Equals in Nonverbal Communication?" Any form of touch usually indicates interest and a desire to spark a romantic connection.

Couples who are flirting with one another will display behavior known as "postural echo" or "interactional synchrony," according to the Social Issues Research Centre. You might both raise your glasses to have a drink at the same time or mirror each other's movements -- behaviors that happen completely naturally and without effort. Synchronized behaviors show you are comfortable with each other and open to taking the relationship further.