Required fields in WordPress consist of two independent systems: visual indicators (asterisks) and enforcement logic. The asterisk alone does nothing to block empty submissions. Client-side JavaScript validation can be bypassed or silently broken by JS errors, caching plugins, or plugin conflicts. Server-side PHP validation is the only reliable enforcement. The post covers how form builders (Gravity Forms, WPForms, Ninja Forms, Contact Form 7), registration plugins, and publishing workflow plugins handle required fields, and explains how Advanced Custom Fields (ACF) provides non-bypassable server-side validation with conditional logic across admin screens, frontend forms, and REST API requests. Common failure scenarios are diagnosed, including missing acf_form_head() calls, max_input_vars limits, and caching issues.
