Document Glossary
Master the technical terminology of modern document management.
AES Encryption
Advanced Encryption Standard. A symmetric encryption algorithm used to protect PDF files with a password. OurPDFEditor supports 256-bit AES for maximum security, making it virtually impossible to crack without the correct password.
Digital Signature
A cryptographic mechanism that verifies the authenticity and integrity of a PDF document. Unlike electronic signatures, digital signatures use public key infrastructure (PKI) to prove the signer's identity and detect any tampering.
Password Protection
A security feature that restricts access to a PDF document. There are two types: user passwords (open password) that restrict opening the file, and owner passwords (permissions password) that restrict editing, printing, or copying.
Redaction
The permanent removal of sensitive information from a PDF document. Unlike simply covering text with a black box, true redaction completely removes the underlying data, making it unrecoverable.
Certificate-Based Security
An advanced PDF security method that uses digital certificates to encrypt documents. Only recipients with the corresponding private key can decrypt and open the file.
Client-Side Processing
A method where all document operations (merging, splitting, etc.) happen within the user's web browser, ensuring data never touches a remote server. This approach provides maximum privacy and eliminates upload/download times.
WebAssembly (Wasm)
A high-performance binary instruction format that allows us to run complex PDF processing libraries at near-native speed directly in your browser. This technology enables sophisticated operations without server uploads.
Server-Side Processing
Traditional method where files are uploaded to a remote server for processing. While sometimes necessary for complex operations, it raises privacy concerns and depends on internet speed.
Batch Processing
The ability to perform operations on multiple PDF files simultaneously. Useful for merging dozens of documents or converting entire folders of images to PDF at once.
Progressive Rendering
A technique that displays PDF content incrementally as it loads, rather than waiting for the entire file to download. This improves perceived performance for large documents.
PDF/A
An ISO-standardized version of the Portable Document Format (ISO 19005) specialized for archives and long-term preservation of electronic documents. It prohibits features unsuitable for long-term archiving such as font linking and encryption.
PDF/X
An ISO standard (ISO 15930) for graphics exchange, specifically designed for the printing industry. It ensures that files contain all necessary information for accurate color reproduction and printing.
PDF/E
A PDF standard (ISO 24517) optimized for engineering documents. It supports 3D models, geospatial data, and other technical content while maintaining long-term accessibility.
PDF/UA
PDF/Universal Accessibility (ISO 14289) ensures PDF documents are accessible to people with disabilities, including proper tagging for screen readers and keyboard navigation support.
HEIC
High Efficiency Image Container. Apple's modern image format that provides high quality at small file sizes using HEVC compression. We provide specialized tools to convert HEIC to PDF and PNG for universal compatibility.
DOCX
The default file format for Microsoft Word documents since 2007. Based on Office Open XML, it's essentially a ZIP archive containing XML files and media. Our converters can transform DOCX to PDF and vice versa.
DPI (Dots Per Inch)
A measure of spatial printing or video dot density. Higher DPI (300+) results in clearer images when converting PDFs to JPG or PNG. For screen viewing, 72-96 DPI is typically sufficient, while printing requires 300 DPI or higher.
Vector Graphics
Images defined by mathematical paths rather than pixels. PDFs use vector technology to ensure text and logos stay crisp at any zoom level, unlike raster images which become pixelated when enlarged.
Rasterization
The process of converting a vector-based PDF page into a grid of pixels (like JPG or PNG) for image editing or web display. This is necessary when exporting PDFs to image formats.
RGB vs CMYK
RGB (Red, Green, Blue) is the color model used for digital screens, while CMYK (Cyan, Magenta, Yellow, Black) is used for professional printing. Converting between these color spaces is crucial for accurate color reproduction.
Color Profile
A set of data that characterizes a color input or output device. ICC profiles ensure consistent color appearance across different devices and media.
Transparency
The ability of PDF elements to be partially see-through. While visually appealing, transparency can complicate printing and increase file size, often requiring flattening before professional printing.
Lossless Compression
A data compression method that reduces file size without losing any original data. Essential for mission-critical legal and medical documents where every detail must be preserved exactly.
Lossy Compression
A compression method that achieves smaller file sizes by permanently removing some data. JPEG image compression in PDFs is lossy, trading some quality for significantly reduced file size.
PDF flattening
The process of merging all layers, annotations, and form fields into a single, non-editable base layer to reduce file size and increase compatibility. This is often necessary before sending PDFs to print services.
Linearization
Also known as 'Fast Web View', it optimizes a PDF to allow the first page to be displayed while the rest of the document is still loading. This restructures the file so page data appears before other objects.
Object Streams
A PDF feature that groups multiple objects together for more efficient compression. Introduced in PDF 1.5, this can significantly reduce file size for documents with many small objects.
Image Downsampling
The process of reducing image resolution in a PDF to decrease file size. For example, downsampling a 600 DPI scanned image to 300 DPI for printing or 150 DPI for screen viewing.
Metadata
Information embedded in a PDF that describes the document, such as title, author, creation date, keywords, and copyright information. This data is searchable and can be edited without changing the visible content.
Bookmark
A named link shown in the navigation pane of a PDF reader, allowing users to jump quickly to specific sections or chapters. Also called 'outlines', bookmarks create a table of contents for easy navigation.
Annotation
Comments, highlights, stamps, or other markup added to a PDF without modifying the original content. Annotations can be added, edited, or removed independently of the base document.
Form Field
Interactive elements in a PDF that allow users to enter data, such as text boxes, checkboxes, radio buttons, and dropdown menus. These can be filled electronically and submitted.
Layer (Optional Content)
Separate content streams in a PDF that can be toggled on or off. Commonly used in CAD drawings, maps, and multilingual documents to show/hide specific information.
Tagged PDF
A PDF with structural information (tags) that defines the reading order and document hierarchy. Essential for accessibility, tagged PDFs allow screen readers to navigate content logically.
Article Thread
A feature that defines the reading order for content that flows across multiple pages or columns, like a magazine article. Readers can follow the thread to read content in the intended sequence.
OCR (Optical Character Recognition)
Technology used to distinguish printed or handwritten text characters inside digital images of physical documents, such as scanned PDFs. OCR converts image-based text into searchable and selectable text.
Font Embedding
The practice of including font data within a PDF file to ensure text displays correctly on any device, even if the font isn't installed. This increases file size but guarantees consistent appearance.
Font Subsetting
Including only the characters actually used in a document rather than the entire font. This reduces file size while maintaining visual fidelity.
CID Font
Character Identifier Font. A font format designed for languages with large character sets, such as Chinese, Japanese, and Korean (CJK). CID fonts efficiently handle thousands of characters.
Glyph
The visual representation of a character. A single character might have multiple glyphs (e.g., different styles of the letter 'a'), and understanding glyphs is crucial for accurate text extraction.
PDF/Office Conversion
The process of converting between PDF and Microsoft Office formats (Word, Excel, PowerPoint). Quality conversion requires understanding document structure, not just extracting text and images.
HTML to PDF
Converting web pages to PDF format while preserving layout, fonts, and images. This is commonly used for archiving web content, creating reports, or generating invoices from web applications.
Print to PDF
A virtual printer driver that creates PDF files instead of sending output to a physical printer. This is the most reliable way to convert any printable document to PDF format.
XPS (XML Paper Specification)
Microsoft's alternative to PDF, based on XML. While less common than PDF, some Windows applications can export to XPS, which can then be converted to PDF for wider compatibility.
JavaScript in PDF
PDFs can contain JavaScript code for calculations, validations, and dynamic behavior in forms. However, this can pose security risks, so many readers disable PDF JavaScript by default.
3D Content
PDFs can embed interactive 3D models viewable in compatible readers. This is particularly useful for engineering, architecture, and medical documentation.
Multimedia
PDFs can contain embedded audio and video files. However, support varies across readers, and embedded media significantly increases file size.
Geospatial PDF
PDFs containing geographic coordinate information, allowing location-based features like measuring distances, displaying coordinates, and integrating with GIS systems.
Portfolio (PDF Package)
A container that combines multiple files of different types (PDFs, Word docs, images, etc.) into a single PDF file with a custom interface for navigation.
Digital Workflow
A paperless process for creating, reviewing, approving, and archiving documents. PDF plays a central role in digital workflows due to its universal compatibility and security features.
Version Control
The practice of tracking changes to documents over time. While PDF itself doesn't have built-in version control, metadata and naming conventions help manage document versions.
Collaborative Review
A process where multiple people review and comment on a PDF simultaneously or sequentially. Comments can be compiled and managed to streamline the approval process.
Preflight
The process of checking a PDF for potential issues before printing or archiving. Preflight checks verify fonts, colors, resolution, and compliance with specific standards like PDF/X or PDF/A.
eSignature vs Digital Signature
An eSignature is any electronic indication of agreement (typed name, scanned signature). A digital signature uses cryptography to verify identity and detect tampering, providing legal non-repudiation.
Audit Trail
A chronological record of who accessed, viewed, or modified a document and when. Essential for legal and compliance purposes, especially in regulated industries.
GDPR Compliance
The General Data Protection Regulation requires protecting personal data. Client-side PDF processing helps achieve GDPR compliance by ensuring data never leaves the user's device.
HIPAA Compliance
The Health Insurance Portability and Accountability Act requires protecting health information. Encrypted PDFs and secure processing workflows help healthcare organizations maintain HIPAA compliance.
Long-term Preservation
Ensuring documents remain accessible and authentic for decades. PDF/A is specifically designed for this purpose, eliminating dependencies on external resources.