PDF forms glossary
Plain-language definitions for the terms that show up when you work with PDF forms. Direct answers, no fluff.
AcroForm
AcroForm is the original PDF form technology built into Adobe's PDF specification. An AcroForm PDF embeds fillable field objects - names, types, positions, default values - directly inside the PDF structure, so any modern PDF reader can detect and fill them programmatically.
Read the definitionXFA (XML Forms Architecture)
XFA is an Adobe-specific PDF form technology that wraps XML-based forms inside PDF containers. It's largely deprecated. Most modern PDF viewers - browsers, Preview, mobile readers - cannot render XFA forms, which is why some old government PDFs only open in Adobe Reader on Windows.
Read the definitionOCR for PDFs
OCR (optical character recognition) converts text inside an image - like a scanned PDF - into machine-readable text. For PDF forms, modern OCR pipelines also detect field boundaries, checkboxes, and signature regions, so a flat scanned PDF becomes fillable.
Read the definitionPDF form flattening
Flattening a PDF form merges the filled-in field values into the page content itself. After flattening, the fields are no longer editable - the values become part of the document permanently, and the file opens identically in every PDF reader.
Read the definitionDigital signature
A digital signature is a cryptographic seal that binds a signer's identity to the exact contents of a document. Unlike a typed name or scanned image, it's mathematically tied to the file - any change after signing breaks the signature.
Read the definitionACORD forms
ACORD forms are the standard PDF templates used across the insurance industry for certificates of insurance, claim notices, applications, and policy changes. Most ACORD forms are flat scans by the time they reach a brokerage or claims team - which is exactly where filling them gets painful.
Read the definitionForm I-485 (Application to Register Permanent Residence)
Form I-485 is the USCIS application a person inside the United States files to adjust their immigration status to lawful permanent resident (a green card). It runs to 20+ pages, asks for years of personal history, and is one form in a packet that usually includes a half-dozen supporting USCIS forms.
Read the definition