In the market, there are many different applications and utilities referred to as "PDF converters". This article will introduce the types and uses of those conversion tools.
Original PDF creation tool from Adobe was a stand-alone application, which could also work with other standard programs (Office among others). In parallel, free tools (Adobe reader) were able to open the documents but not to modify them.
Since the creation of the PDF file format, several companies have issued applications for creating and editing PDF files, with most of them based on GhostScript code.
Nowadays, with PDF being an open format, more features are being added everyday, so that for example, interactive 3D CAD images can be viewed (rotated, scaled, etc.), or rather standard forms can be filled-in by the user in order to be considered as official documents. However, this can be a drawback, if any application does introduce deviations from the standard format definition.
However, the main stream of PDF creators is currently the print emulators.
Those are utilities that are installed in the operating system, and work exactly as an added printer (using WYSIWYG - what you see is what you get) with specific setting: Document protection, watermarking, owner and user rights, etc. can be defined, prior to the PDF conversion.
In this case, it is very easy to convert, for example, from Word to PDF, just by opening the DOC, and "printing" it with the converter utility.
However, some new possibilities are appearing in the PDF arena.
On one side, specific applications as PDFTKbuilder (a portable version can be obtained from Portableapps.com) can convert almost any document to PDF (again, with GhostScript code), adding some functions like documents merging, watermarking, read and print protection. The required documents must be selected, then only an output file name and path are needed.
Of course, there are free online tools - in this case, the files are uploaded to specific webs (for example, Freepdfconvert.com), and the result is downloaded to the computer.
Finally, some applications try to offer most of the above-mentioned functionality. Again, Adobe Acrobat is the main player in the market, but its high price has made several development teams in order to produce alternative programs.
One of the most successful ones is Nitro PDF (Nitropdf.com), which has a free version available. It allows for direct PDF view and creation, merging of several files, watermarking, print/copy protection.
These all-in-one applications may be the perfect solution for offline computers, or for the creation of PDF files from big documents.