A pay period is the stretch of time over which employee work hours are compiled for later inclusion in a paycheck. This is typically a standardized period, such as a weekly, biweekly, semi-monthly, or monthly period. It is more efficient for an employer to avoid a weekly pay period, since this requires the preparation of 52 paychecks per year. Conversely, employees may object to a monthly pay period, since they are only paid 12 times per year. These conflicting pressures lead many employers to adopt a biweekly or semi-monthly pay period. An employer can have different pay periods for different groups of employees. For example, hourly workers may have a weekly pay period, while salaried workers have a biweekly pay period.