PDFs are everywhere these days. They're used by the IRS for downloadable tax forms. They're used when consultants send proposals and contracts to clients. They're even used for ebooks! But do you know how to make them? If you have Adobe Acrobat, the answer is probably yes ... but if you're furrowing your brow and thinking that you really have no idea how to make a PDF, then you're in luck. Below are three free, open source pieces of software that you can download and use right away.

No fuss, no muss!

LibreOffice

This first option, LibreOffice, might seem like an obvious choice if you're already familiar with open source, but if you're new to the community, it's definitely worth looking at. LibreOffice is one of the flagship open source projects, and it's a great alternative to Microsoft Word, Excel, PowerPoint, Visio, and Access ... and, since it allows you to import and export PDFs, it's also a great alternative to Adobe Acrobat.

LibreOffice is available for Linux, Microsoft Windows, and OS X, and you can download the installation files from the official Download page. You can also download the source code (which was released under an LGPL license) from the LibreOffice website.

PDFCreator

Unlike LibreOffice, PDFCreator is a piece of software designed purely to deal with the creation and control of PDF documents. The interface is quite simple to use, and because it all revolves around PDFs, there are several additional features that might be of interest. For example, you can add passwords to files, encrypt files, stop people from printing and/or modifying documents, add digital signatures, and save various profiles for quick access to settings.

PDFCreator is a fully functioning piece of software, and if you end up getting more involved with PDF files, you can also download its companions -- PDFArchitect (which lets you modify PDF files) and Images2PDF (which lets you convert images to PDF files).

Now, there is a downside to PDFCreator, and that's that it's only available for Microsoft Windows ... but if you're a Windows user, you can download the installation files from the official Download page. You can also download the source code (which was released under a GPL license) from Sourceforge.

PDFLite

And, finally, we have PDFLite, another piece of standalone software, but this one is focused on minimalism. The interface is simple (but it does let you search, print, and zoom), and in terms of what it can convert, keep this line from the main page in mind: "Any program that can print, can convert to PDF." Plus, since the web is full of PDFs, the creators of PDFLite have created plugins for the Microsoft Windows versions of Chrome, Firefox, and Safari, which might make your browsing a little more seamless.

Unfortunately, PDFLite is only available for Microsoft Windows, but if you'd like to download and install it, you can get the installation files from the official site. If you'd like to download the GPL-licensed source code, you can get that from the main site, too (just scroll down to the bottom and look for the "Source Code" link under the "Development" heading).