Bitcoin is an online currency which uses peer-to-peer technology for payment transfers. Its price is varying over time and if you have some investments in Bitcoins, you should keep an eye on it. Rui Santos suggests using ESP8266 programmable WiFi module to check Bitcoin price. The idea is pretty simple. He programmed WiFi module as HTTP client which regularly requests Bitcoin price by using JSON API.
ESP8266 is fairly to program. All you need is to flash it with NodeMCU firmware which then allows programming module with LUA script which is somewhat similar to Arduino concept. With only few lines of code you can connect to internet, control GPIO and do other crazy things. This following script can be used as base for other HTTP client projects like weather, finances or other extraction.