olemus
veebilehe sisestusväli, mis on inimkasutajale nähtamatu, kuid mida "näeb" ja täidab spämmirobot
= an input field on a web page that is invisible to a human user but can be "seen" and filled in by a spambot

ülevaateid
https://www.reviewmylife.co.uk/blog/2008/05/30/hidden-field-spam-trap-for-phpformmail/

https://blog.horizonweb.co.uk/2007/07/how-to-stop-spam-bots-with-formmail-and.html