wpsnoop [signup_form] shortcode is used by 1 plugin

WordPress Shortcodes are used to create visual effects like [bold] text [/bold]

Shortcodes can also be used to embed Videos, Calendars, Tables, Products, Product Reviews, GitHub badges, source code, almost anything - and therein lies the great benefit of WordPress shortcodes and also the problem of conflicting plugins competing to try to make [signup_form] a shortcode appear on a page.

This page provides some information on the signup_form shortcode and a list of plugins and themes that implement it.