The "Hours of Service" (HOS) regulations are rules set by the Federal Motor Carrier Safety Administration (FMCSA) to ensure that commercial drivers do not drive for too long without taking breaks. These regulations help prevent fatigue-related accidents by limiting the number of hours a driver can operate a vehicle in a given period. Under HOS rules, drivers must take mandatory rest breaks and cannot exceed a certain number of driving hours per day and week. For example, a driver can drive a maximum of 11 hours after taking 10 consecutive hours off duty. These guidelines are crucial for maintaining safety on the roads.