(Credit: Bruce Mars)

And once content is saved as a PDF, its formatting is fixed and can't be changed by the reader. So, when you create a PDF you can use a wide range of fonts, set the layout and design of each page to suit you, and be sure that what you create is what the recipient will see. And the document is locked down, so you know that your recipients can't change add or delete anything in your file. And with the ability to create fillable forms and have embedded web links in document, PDF is also versatile.

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Because the format can serve so many functions, it's not a bad idea to have a PDF creator and editor at their fingertips. The best known of these is Adobe Acrobat, but it comes with price, and there are many other full-featured and affordable alternatives.

If you only want to create simple PDFs, or make simple edits to existing ones, then Microsoft Word (Windows) lets you open PDFs, convert the document to the Word file format, edit, and then save back to PDF without spending any extra money. But if you want to go well beyond Word's PDF functionality, the following apps are up to the task.

1. Foxit PhantomPDF

PhantomPDF (Windows) is a competitively priced PDF creator/editor ($129, or $7.99 a month), considering the range of features on offer. As well as creating directly with the application, you can import files created in other documents such as Microsoft Word, Excel, and PowerPoint, and export either a whole PDF or a selected area to those formats and others including HTML and RTF. Several PDFs can also be merged to create a new document.

The editing features are particularly comprehensive, with the ability to bulk-remove web links, use multimedia annotations, search and replace, and spell-check among them. The software is easy to navigate thanks to its ribbon-style user interface.

A more expensive Business (Windows) ($159, or $8.99 a month) adds more advanced editing features such as image editing, higher compression rates and layer management.

(Credit: Phantom)

2. Nitro Pro 12

Nitro Pro (Windows) pitches itself squarely as an alternative to Adobe Acrobat, and is a power user's solution, with features like batch creation of PDFs and the ability to edit image properties (brightness, colors, and so on) among its document-creation highlights. It also has a good array of usability features such as the ability to create editable text from scans via OCR, collaboration features like annotations, spell check, and the ability to automatically compare PDFs to identify differences between them.

With multiple windows open it's easy to drag-and-drop text and images between documents, making document creation fast and efficient. A direct connector to Microsoft OneDrive for Business makes it easier to share files with other people, and there are strong document security features, including encryption and digital signatures. All for $190.80.

(Credit: Nitro)

3. Nuance Power PDF

Nuance Power PDF (Windows) is a feature-rich PDF creation and editing application, with a range of features for $129.99 that will suit more advanced PDF users. It's easy to combine separate documents into a single PDF, to rearrange pages within a PDF, and to create -- and fill in -- PDF forms. The ribbon-style interface has two modes, one for mouse-driven use and a "touch mode" with well-spaced menu items for finger-friendly use on tablet or laptop touchscreens.

The Advanced version, starting at $179.99, includes support for DocuSign electronic signatures, redaction of sensitive information, and networking capability, making it a suitable choice for office as well as home use.

(Credit: Nuance)

4. Ashampoo PDF Pro

With Ashampoo PDF (Windows) you can create PDFs directly in the application, without the need to convert from another format. There's a built-in spell checker to help prevent embarrassing mistakes, and collaboration tools that allow more than one person to work on a document. (For $30, three users can share the app.) You can also convert PDFs into text documents so that you can do further editing in Word or another application of your choice (it converts to Microsoft Word and RTF, for example) and then bring them back into Ashampoo PDF Pro for final tweaking.

For more sophisticated PDF creation, you can build PDFs by dragging and dropping from multiple source documents, while its optical character recognition (OCR) capability allows you to convert scanned material into editable text.

(Credit: Ashampoo)

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Sandra Vogel is a contributing writer for ZDNet and CNET's She writes about mobile technology, the latest apps, Microsoft Windows, and more.