What is a PDF?
PDF (Portable Document Format) is a fixed-layout document standard created by Adobe. A PDF packages text, vector graphics, fonts, and images into a single file that renders consistently across devices and operating systems. PDFs are the default format for invoices, contracts, ebooks, and printable web pages.
Why PDFs are everywhere
PDF preserves layout — line breaks, fonts, and images stay in place unlike reflowable HTML. That makes PDF ideal for legal documents, tax forms, and brand-controlled marketing PDFs where pixel-perfect output matters.
Browser-based PDF tools
Modern web apps can merge, split, and convert PDFs using JavaScript libraries such as pdf-lib and PDF.js. Processing happens in Web Workers or the main thread without sending files to a server, which improves privacy and reduces latency for small and medium files.
Limitations to know
Scanned PDFs are images, not selectable text — OCR is required for search and copy. Heavy compression may reduce image quality. Password-protected PDFs need the correct password before editing.