Sexual arousal (also sexual excitement) is the arousal of sexual desire, during or in anticipation of sexual activity. Things that precipitate human sexual arousal are called erotic stimuli, or colloquially known as turn-ons. There are mental stimuli and physical stimuli such as hormones which can cause a person to become sexually aroused.
Sexual arousal may not lead to any actual sexual activity, beyond a mental arousal and the physiological changes that accompany it. Given sufficient stimulation, sexual arousal in humans will typically end in an orgasm; but arousal may be pursued for its own sake, even in the absence of an orgasm. It is thought that women may get more aroused at a certain time during their menstrual cycle, either before, after or during their period, however, there are studies that do not support this theory[1] .
When men are aroused they typically get an erection. When women are aroused, they typically get vaginal lubrication (wetness).