 So, what is PDF? A PDF stands for Portable Digital Document Format, which is one of the most commonly used file types today. In a world with varying operating systems, screen sizes, browsers, and hardware components, the PDF stands firm and unchanging. Knowing that the document you created won't go through any weird changes before your viewer sees it is comforting. That's what the PDF provides and thus it's been the standard for over two decades. A PDF file encapsulates a complete description of a fixed layout fled document including text, phones, vector graphics, and images and other information needed to display it. Now, let's try to understand it in detail. So, let's start with a Portable. As the name implies, a PDF can be read by almost all of the screen devices which are available today. That includes all flavor of computers from Windows to Mac to Linux. And mobile devices like iPhone, iPad, Android, Windows Surface and many more. And even most handheld e-readers like Kindles and Nooks can also read PDFs, though they can rarely display the interactive elements of PDF. Next is Visivik. Means what you see is what you get. Meaning, let's say you design the page in some third party software. Now when you convert it to PDF, the page will appear as is after conversion. You will get a pixel-perfect reproduction in PDF form of any document, inclusive of the phones, images, or any vector objects. And then next is a PDF is self-contained. In fact, a PDF is as much a container as it is a presentation format. Anything that makes up a PDF is contained within the PDF itself. The phones to render the text properly, the images on the page, the forms with their fields, the scanned documents, and even any file attachment you may include like Excel documents or text documents or Word files or ZIP files. They all are included inside this single PDF. Next is Compression. The PDF format has built-in compression to make the file size as small as possible even with embedded phones, images, and other objects. ByteScouts free utility PDF multi-tool have already provided this feature to compress big PDF files. Accessibility. Accessibility is an automatic part of the PDF creation process. The text within PDF stays text. That means search engine or some assistive devices such as screen readers or ByteScouts document parser template editor tool can interpret, parse, and present the information in the text in various ways. Accessibility can be disabled. That means you can make PDF unsearchable. Well, again ByteScouts free utility PDF multi-tool have already provided this feature. And the next is Security. The files that are in PDF can be protected by passwords. There are times when a client needs to share some secret information with the company. They can easily convert the file to PDF format and have it password protected. It will be no problem of privacy in that matter then. And last but not the least PDF are stable. The PDF file format and file specification have been around since the early 1990s. PDF is in fact an open standard which means that though Adobe had created PDF but there are few hundreds of other companies and individuals have built their own applications that create and manipulate and display PDF. ByteScout have already provided many tools and a very rich API named PDF.co to manipulate PDFs. We will see that demo in this course later on. The world will still build reliable PDF reading software to access all the information already in PDF form for at least the next two centuries. Hence PDF is an extremely stable, reliable and a standard file format for any information. You won't have to worry that a PDF document you create today will be outdated or unsupported a year or a two or a five from now. And these are the enough reasons why PDFs will still enjoy so much popularity.