Unlimited annual leave was a workplace benefit first introduced in Silicon Valley which allows employees to take off as many holiday days as they wish. It was considered an innovative concept at the time, similar to remote work before the COVID-19 pandemic. Companies that provide unlimited annual leave typically allow their employees to take as many days off as they wish, with the expectation that all of their work is completed. 

Unlimited annual leave may sometimes be called "unlimited PTO" (paid time off), offering employees greater flexibility regarding their work-life balance. Employees can better manage their workload and personal life with no set limit on the number of days off they can take. It is also seen as a way for companies to attract and retain talent, as it offers a unique and desirable benefit that sets them apart from other companies. 

However, there are potential drawbacks to this policy as well. Some employees may feel guilty or unsure about how much time off is appropriate, leading to burnout or a reluctance to take any time off at all. Managing workloads and schedules can also be challenging when employees take varying amounts of time off. Most often than not, employees would also end up taking less than the statutory amount, which is why some companies set a minimum number of days to take.