PDF CREATION (PDF, PDF/a, PDF/x)
Invented by Adobe Systems and perfected over 20 years, Portable Document Format (PDF) is now an open standard for electronic document exchange maintained by the International Organization for Standardization (ISO). When you convert documents, forms, graphics, and web pages to PDF, they look just like they would if printed. But unlike printed documents, PDF files can contain click-able links and buttons, form fields, video, and audio — as well as logic to help automate routine business processes. When you share a PDF file, virtually anyone can read it using free Adobe Reader® software or the Adobe Reader mobile app.
Source and further reading with Adobe Acrobat Free download can be found here.