Arduino Uno with Wifi
Arduino Nano with WiFi

What is Arduino? Arduino is a Open Source hardware and software microcontroller circuit board.
What can Arduino be used for? Arduino microcontrollers can be useful in prototyping electronics for the likes of Internet of Things.
How does Arduino make development easier? Arduino includes inputs, outputs, timing, communications, analogue measurement and USB programming.
Programming is via USB cable. The program runs once power is supplied to the Arduino circuit board.

Arduino microcontrollers by popularity by descending sales from

PopularityDescriptionCost US $
1Arduino Nano V3. Separate headers. 2 x 15 pins package size. 14 digital input / outputs. 8 analog inputs. Mini USB connector.2.15
2ESP8266 Wifi compatible with Arduino Nano. 2 x 15 pins package size. Image on the top right.3.78
3Arduino Uno R3 compatible (first Arduino design). 14 digital input / outputs. 6 analog inputs.3.24
4Arduino Mega 2560 compatible. 54 digital input / outputs. 16 analog inputs.7.29
5Arduino Mini 328 compatible. 2 x 12 + 6 pin package size. Separate headers.1.63
6Wemos D1 Wifi Arduino Uno compatible. Image on the top left. Similar to Arduino Uno with added WiFi. Micro usb connector.3.58
7Arduino Micro compatible. 2 x 12 pin package. Micro usb connector.2.91
8Arduino Leonardo compatible. (Simpler version of Uno) Micro USB connector. 20 digital input / outputs. Better USB device support.4.40
9Arduino Due R3 compatible ARM 54 input output pins. 54 digital input / outputs. 12 analog inputs. 84 MHz ARM processors (much faster).14.15
10Arduino Yun compatible. Linux, Ethernet, WiFi, microSD storage. This can act as a small web server (edge computing).56.05
11Arduino Yun as a communications shield with Linux, Ethernet, Wifi and microSD storage. This works with Arduino Uno / Leonardo / Mega.27.75