Developers who are still using the Google reCAPTCHA v1 API need to switch to the reCAPTCHA v2 API as the v1 API will shut down in March 2018. The service uses machine learning and its advanced risk analysis engine to figure out if users completing forms and other actions are humans or bots.
Sometimes what is happening now is not as important as what happened then. I am speaking of the past and how it can help you piece events together. This what makes Gnip’s newest Twitter search API so powerful.