What is Form (AcroForm)
PDF can support interactive and non-interactive forms.
Interactive forms, also known as "AcroForms", were added in PDF 1.2 and consist of fields that allow users to input information. These fields can appear on any combination of pages within a PDF document and can be exported/imported as FDF or XFDF.
Non-interactive forms, introduced in PDF 1.7, are static representations of form fields that can include data from external sources or be intended for manual filling.
For more technical information, refer to clause 12.7 in ISO 32000-2:2020.