Honeypot (Spam Protection Without Captcha)
A honeypot is a form field that is invisible to people but reachable for automated form bots; if it is filled in, that gives away a bot script, without real users having to solve a captcha.
In practice
Honeypots count as a data-minimising, user-friendly alternative to conventional captchas, because they load no third-party scripts and demand no extra interaction from genuine visitors. Combined with server-side rate limiting and CSRF protection, a honeypot forms solid basic cover for contact forms.