Most employees in the United States are under an "at will employment agreement." Specifically, this means that they serve at the pleasure of their employer, who can fire them or lay them off for any reason, or for no reason. Oftentimes, the employer will tell new employees that they are at will. Even if they do not, unless the employer explicitly states otherwise in its official policies, states assume that employees are at will for legal purposes. However, even at will employees have rights. Possibly the most important is that employers cannot fire or harass workers because of their age, race, sex, or religious background. Further, an employer could be held liable if it can be proven that he has sexually harassed employees.