AirPort Utility is a built-in Mac app that is used to configure and control Wi-Fi networks using Apple’s AirPort Extreme, AirPort Express, and Time Capsule. The AirPort Extreme is a base station router like you would use when setting up your Wi-Fi network. An AirPort Express is used to extend a Wi-Fi network to a larger area, or can be used to stream audio using AirPlay. A Time Capsule is a combination of an AirPort Extreme and an external hard drive, and comes in 2 TB or 3 TB. It automatically backs up all Macs on your network.
AirPort Utility has the ability to set limits on what time of day the network (and therefore the internet) can be accessed from specific wireless devices. This can be helpful in situations where parents want to keep kids off of the internet after a certain time. Time limits can be set for different times on different days of the week.