See How Does my Android Device Connect Over Wi-Fi? for a short explanation.Some App Inventor users have solved this problem by purchasing a wireless router and setting up their own local network. These include some hotels, conference centers, and schools, that configure their wireless networks to prohibit two devices on the network from communicating with each other. There are, however, some environments where wireless connections won't work.
(See Option 1, under Setting up App Inventor.) It does not require any additional software to be installed on your computer. This is the method strongly recommended by the App Inventor team. The Companion can communicate with your computer over a wireless connection. The instructions below (Step 2) explain how to install the companion. This communication is managed by the AI2 Companion App running on the device. When you use App Inventor with a phone or tablet, that device communicates with the App Inventor software running in your computer's browser window.
