Iot (Internet of Things) is a development of the Internet, where everyday objects are connected to the network and can exchange data. In short, this means that any device can connect to the network, which is made easier with these WIFI modules.
Loyer ChristianSONOFF RE5V1C - 5V wifi inching/selflock relay moduleEasy to order, fast delivery. A user manual attached to the modules would have been appreciated, or at least a link to a site giving configuration explanations.
WouterESP8266 ESP-01S WIFI ModuleDifficult to find clear information about getting this module working. Furthermore, it works excellently.