But what constitutes being unfaithful differs among men and women, according to a new survey.

Actor Matthew McConaughey and Jessica Alba were named as the most likely celebrities who could lead people astray.

Most people questioned in the poll agree physical contact -- including kissing someone other than your partner -- means you are cheating. But 77 percent of women also think using the Internet for online sexual talk or cavorting in front of a Webcam is also cheating, compared to only 57 percent of men.

"We've always had the inside scoop about what's on the minds of women everywhere, especially when it comes to relationships, said Deborah Fine, president of iVillage Inc, a media firm dedicated to women which conducted the poll with MSNBC.com.

"This new survey gives us a closer look at how both men and women feel about the not-so-warm-and-fuzzy topic of fidelity," she added in a statement.

Nearly three-quarters of women also feel sending flirtatious emails is cheating, as opposed to 53 percent of men.

According to the online survey of 70,288 people, the most common cheating partners are friends and co-workers. Money is also an element in deceitful behavior because the higher a man's salary the more likely it is that he will be unfaithful.

But the same does not apply to women.

Actor Matthew McConaughey and Jessica Alba were named as the most likely celebrities who could lead people astray. But one in 10 men and women said Angelina Jolie was their object of desire.

"The good news is that most of us fear cheating more than we really need to," said Julia Sommerfeld, of MSNBC.com.

"People overestimate the rate of cheating by nearly double."

Men said they usually strayed because they wanted more sex, while women sought emotional attention.

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