At its most basic, a Content Management System (CMS) is a software program that makes building and maintaining websites faster and easier. Let’s say we’re using a site without a CMS—if we want to post an event and have that event show up in five different places on the site, we have to perform the same activity five separate times on five separate pages. With a CMS, we only have to post the event once—and any staff member can do it, regardless of their technical expertise.

How does this work?Content management systems store the actual content (text and images) in a database. The system can then automatically pull the content out and show it on the appropriate pages based on rules you set up in advance. The ways you can organize it, and the types of rules you can use, depend on how structurally flexible the CMS is. This setup makes it easy for all your content administrators— the staff members writing and publishing the actual information on the site—to create content without worrying about technical issues, or even knowing all the places the content should go.

Content Management Systems also separate graphic design from the content itself. This is accomplished through the use of “themes,” or graphic design layers that control graphic elements, font and navigation styles, and page layouts for each page on the site. we can simply choose a pre-packaged theme for our site, or create a theme that’s completely customized to our own look and needs.

The term “open source” is a key distinction. It means the software’s source code is freely available for everyone to see and change (as opposed the source code for Windows 7, for example), but it also has many wider implications. While proprietary software is created, distributed and maintained by a business, with open source software these tasks are handled by a community of developers and users (recently, for-profit consulting and development firms have also become important vehicles for support). Just how effective that community is at its job is an important consideration when choosing an open source CMS.

Open source content management systems are free in many ways. They’re free as in “free speech”—you can do what you wish with the product and the code behind it, extending and integrating it as you see fit. They’re free as in “free beer”—there’s no license cost for the software, and anyone can download and install them on a web server without cost, though you’ll likely need to pay for the server, or pay someone to install the system. And they’re free as in “free kittens”— that is, an open source CMS takes work. You’ll either need to put a lot of time into implementing and maintaining your system, or hire someone to do it for you. No CMS will magically design and write your whole site for you; that’s a job for humans. Open source content management systems are also designed to be modular. When you download one you get the set of features a group of developers decided ought to be the base level of functionality, called the “core” of the system. But there’s a huge range of add-on modules that provide additional functionality for each CMS, and a rich network of developers working to create more. If there’s something you want for your website that the core CMS doesn’t already do, someone else has probably already built what you’re looking for—and, if not, you can build your own, or hire someone to build it for you.

There’s a whole community of people who create addons, modify source code, and ask for and offer support. When you decide to install an open source CMS you become a part of that community. But there’s an expectation that when you ask a question, you have at least some knowledge of the system; they’re not going to do the work for you. If you don’t have someone with technical skills on staff, you may want to hire someone to implement the CMS. And as we’ve noted before, if you’re planning on building a simple site, the person you choose to implement the CMS is considerably more important than the CMS itself.

An open source CMS certainly isn’t a cure-all; it may not even be the best option. But for many organizations, it can offer useful savings in time, money and resources.