This app allows to wake up computers and other devices that support the WOL (Wake On LAN) standard. Most modern computers do support this, however, you may need to enable Wake-On-LAN in BIOS and sometimes in network card driver preferences. Although the app itself is very easy to use some networking knowledge may be required to set up your devices, especially if you are walking up over the Internet. To wake up a computer on your local network, all you need to provide is your device's MAC address. The app will figure out the broadcast IP address and send WOL packet to all devices on the network. You can also specify your device's local or broadcast address manually. To wake up a computer over WAN you have to provide your router or firewall's external IP / DNS address. You must also configure the router to forward WOL packets to your local network. Simple port forwarding is not always sufficient. It may require forwarding UDP port 9 to your local broadcast address, setting up MAC-IP, MAC-ARP reservation, or something similar. Not all methods work on all routers and some more basic routers may not allow waking up over WAN at all. For more information about how to implement WOL check here: http://www.mysysadmintips.com/windows/clients/84-implementing-wol