The UART OBLOQ is an Internet of Things module module from DFRobot. It is based on the famous ESP8266 WiFi enabled SoC  and exposes a command based interface over Serial. The device is shown in figure 1.
So, in other words, the ESP8266 of the UART OBLOQ is running a custom firmware that receives commands via serial and is able to interpret them and act accordingly. This firmware comes already flashed in the device, so we don’t need to flash it ourselves.
This means we can connect another microcontroller to the UART OBLOQ and offload from it the WiFi related functionalities. For example, we can develop an application in an Arduino board and then interact with the UART OBLOQ to send messages to remote applications over the Internet.
Currently, in version 3.0 of the UART OBLOQ firmware, we can use MQTT and HTTP as protocols to communicate with other devices and applications. Note however that, since the UART OBLOQ is based on the ESP8266, it is possible that, in future firmware versions, more communication protocols can be implemented.
The UART OBLOQ can operate with a supply voltage between 3.3 V and 5 V and a current of less than 240 mA . This means that we need to use a power supply capable of providing a considerable amount of current for it to operate correctly.
It is a relatively compact device, with the dimensions of 35 mm x 32 mm and a weight of 16 g .
The device already includes an antenna, which means the WiFi functionalities can be used out of the box without the need for additional connections or soldering.
The UART OBLOQ exposes a minimalist interface with only 4 pins. Two of them are for power supply (GND and VCC), and the other two are the Rx and Tx pins of the Serial interface .
The device operates with a baud rate of 9600 , so this needs to be taken into consideration when establishing a serial connection to it.