Let's begin with Drupal.
This is the name given to the second most widely used (behind WordPress) open source Content Management Systems (CMS) for general web development. Created in 2001, Drupal is now — as we enter 2014 — a fully mature CMS in its 7th major iteration (version 8 is currently in development).
Drupal is an English rendering of the Dutch word "druppel", which means "drop" (as in "a water droplet"). The name was taken from the now-defunct Drop.org website, whose code slowly evolved into Drupal.
So -- what's a "theme"?
In the world of Content Management Systems, the word "theme" refers to the collection of files (style sheets, various page templates, specially coded function files etc) that together comprise the 'theme." These files work together programmatically to produce the interface or public part of the website, both visually and functionally. A theme includes files that define (and can be modified to define) the site's layout, color palette, typography and presentation of content within the layout etc. Themes also include files that define (and can be modified to define) how certain elements work -- like a slideshow, drop-down menu etc.
Are there different types of themes?
Yes, generally there are 3 types of CMS themes (also holds true for WordPress, Joomla etc). These are free, premium and custom.
- Free themes are available to anyone at no cost. These are not recommended for professional use: they may contain malware code (designed to invite hi-jack software etc) and are sometimes not well coded.
- Premium themes are ones that cost money (approx $40-$100) and are usually well built, offer plenty of nice features, additional support and periodic updates etc. Because Drupal and its themes are open-source, a premium theme's code can be modified for any reason -- mainly for purposes of making changes to its function and/or appearance. Premium themes offer several advantages: the code is already in place and ready to serve as a solid foundation for client customization and extra features may be included which means that the developer doesn't need to research and install these. These advantages also translate into cost savings for the client.
- A custom theme is one which is designed and coded from scratch. Their main advantage is that the design and function can be (and usually are) completely original and can meet a client's exact needs. The main disadvantage is their greater (than a premium theme) cost.
Are there different types of theme designs?
Yes. Theme designs (like like all websites) fall into different (somewhat loose) categories of design. Typical theme designs include Magazine themes, Portfolio, Business, Real Estate, Wall, Ecommerce etc. An ecommerce theme, for example, may include extra, integrated features such as shopping cart software, a product page template etc.
What does the word "responsive" mean in terms of a theme?
In the old days of the web (say, before the iPhone -- or around 2007), the Internet was primarily viewed on desktop or laptop computers. This meant that for easy viewing, website design needed to accommodate only a few different monitor sizes. (The basic rule was to design for a screen width of about 960 pixels.)
But with increased use (especially including globally) in recent years of smart phones and tablets as primary viewing devices, it's now become standard practice to design sites so that they automatically "respond" to a variety of screen sizes, presenting an optimal, easy to read view for each size. So . . . a "responsive" website design or build refers to one which will -- normally without user input -- be easy to read and use on any device regardless of display size.
How do I know if a theme is responsive, without looking at it on my smart phone?
Open the theme's live demo (usually available as a link when viewing themes) in your browser. Make sure that your browser isn't maximized, but only fills part of your monitor's screen. Then, position your cursor at the lower right corner of the browser window (you'll see the cursor arrow convert to a double-side arrow). Left click and drag the browser screen toward the upper left of the screen.
As you do this, you should see the theme change shape: for example, the horizontal menu may disappear and change to a tiny box with 3 lines (called a "hamburger button"); horizontal layouts may begin to stack up vertically and so on. In other words, you'll be able to get a very good idea of how a site might look display on a smart phone. Conversely, if the site's content doesn't resize and can't be read (or seen) when resized, you'll know that the site or theme isn't responsive.
For more information, see http://en.wikipedia.org/wiki/Drupal
Note: Site Shack no longer builds non-responsive websites and almost all themes at this time are built using responsive design (or coding).