What is Portable Document Format?

PDF (Portable Document Format) is a file format used to represent documents in a manner independent of application software, hardware, and operating systems. Each PDF file encapsulates a complete description of a fixed-layout flat document, including the text, fonts, graphics, and other information needed to display it.

Acrobat's PDF files are more than images of documents. Files can embed type fonts so that they're available at any viewing location. They can also include interactive elements such as buttons for forms entry and for triggering sound and QuickTime or AVI movies. PDF files are optimized for the Web by rendering text before graphic images and hypertext links.

PDF files are created using Adobe Acrobat , Acrobat Capture, or similar products. To view and use the files, you need the free Acrobat Reader, which you can easily download. Once you've downloaded the Reader, it will start automatically whenever you want to look at a PDF file.

In 1991, Adobe Systems co-founder John Warnock outlined a system called "Camelot" that evolved into PDF. While Adobe Systems made the PDF specification available free of charge in 1993, PDF remained a proprietary format, controlled by Adobe, until it was officially released as an open standard on July 1, 2008, and published by the International Organization for Standardization as ISO 32000-1:2008.

In 2008, Adobe published a Public Patent License to ISO 32000-1 granting royalty-free rights for all patents owned by Adobe that are necessary to make, use, sell and distribute PDF compliant implementations

PDF files are especially useful for documents such as magazine articles, product brochures, or flyers in which you want to preserve the original graphic appearance online. A PDF file contains one or more page images, each of which you can zoom in on or out from. You can page forward and backward.

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 clickable 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.

Key Features of PDF

1:When you use PDF files to communicate, you don't have to worry about whether people have the same software you used to create your originals.

2:The integrity and longevity of the more than one billion PDF files in existence today is ensured by the ISO 32000 open standard.

3:Businesses and government agencies around the world use PDF as a standard format for exchanging documents more securely. You can, too. unlock pdf mac and crack pdf mac

4:You can view and interact with PDFs on virtually any platform, including Windows?, Mac OS, and mobile platforms including Android? and iOS for iPhone and iPad.

5:Virtually anyone can electronically sign PDFs using free Adobe Reader XI software or Adobe Reader for mobile.

6:When you need to find a particular word or phrase in a PDF, it's easy to search text and metadata, including scanned text that was converted using optical character recognition (OCR) technology.

7:The PDF specification has been expanded to work with assistive technologies, making PDF files more accessible to people with disabilities such as low vision or blindness.

8:Whether your business needs a specialized solution for integrating PDF files into daily workflows or you'd like to receive training or consultation on the most efficient use of PDFs support is available.

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OCR is short for Optical Character Recognition, conversion of images of text into characters. It is used to extract text from scanned images of type written, handwritten, or printed text. Briefly speaking, it is used to digitalize these scanned books and documents. OCR makes scanned text editable and searchable.
Why OCR technology is important?
OCR is indispensable in working, education and publishing. OCR enables users to convert contracts, receipts, invoices, survey reports into electronic files for more conveniently management. OCR makes it easy for teachers to quote data from journal. For some old paperbacks and hardcover, OCR can change these books into e-books. Many public domain books in Google Books are digitalized by OCR technology. All in all, OCR plays an important role in converting scanned images into editable electronic files.
OCR software
Since electronic file become the common used file format in daily life, many online OCR services and desktop OCR apps are developed quickly.
Online OCR service is a new trend today. It is developed to meet the requirements of both individual users and enterprise customers' needs. Just like the progress of the development of phones. First for enterprises, then it becomes the commonest stuff in daily life. Most online OCR services are free of charge. Users are allowed to import scanned files and get the same files in new formats. Here are some free online OCR services:
Desktop OCR apps are still the main stream in OCR world, because these apps allow users to convert their scanned files freely and privately. Contracts, invoices, receipts are sometimes confidential files. For these files, users would better use desktop apps to perform OCR.
As I've mentioned OCR apps, I have to say a few words about OCR tools for PDF, since PDF is the most widely used file format for electronic files. There are hundreds of online services and free apps for converting scanned PDF to editable formats, like Word, Excel, PowerPoint, EPUB and so on. If you need to perform OCR to convert your PDF files, I still recommend desktop OCR apps, like WondersharePDF Converter Pro. Generally, desktop apps perform better than online services.

Tips for OCR
Though OCR technology has been developed more than 30 years, during the process of performing OCR, you still need to take care. Image-based files should be shot or scanned with high-resolution, simple background and plain text.

You can use google to search for more info about it. http://www.pdf-file-converter.com/ocr/