How to connect Arduino Uno to wifi?

I have Arduino Uno with starter Kit. I have "love a meter" done and temperature can be displayed in serial monitor in MacBook. Currently I have no internet connection in Arduino.

What part I need to purchase to connect Uno to Wifi?

If you like, please provide link to product from http://www.ebay.co.uk/ or from other place.

The cheapest way is probably with an ESP8266 module.

You can also get WiFi shields that are more expensive but are easier to connect to an Uno.

There are dozens (maybe hundreds) of Threads on the Forum about both.

...R

The cheapest and easy way is using a WeMos D1 Wifi Uno. It includes esp8266 12-e module and of course, you can use it like a standalone board, don't need UNO. It probably already is available on ebay UK.