reCAPTCHA protects your website
reCAPTCHA uses an advanced risk analysis engine and adaptive challenges to keep malicious software from engaging in abusive activities on your website. Meanwhile, legitimate users will be able to login, make purchases, view pages, or create accounts and fake users will be blocked.
Google ReCapture enables users to protect the forms on their sites from spam. The ReCapture setup requires a Google recapture account and a site and security key, which need to be inputted into the relevant fields.
You can read all about getting your ReCapture site and security key from Google here and how to add ReCapture spam protection to the forms in your Blocs site here.