A WordPress Theme defines the ‘look and feel’/style of your WordPress Website. A WordPress Theme is more than just the Stylesheet (CSS) in that it defines widget areas, where certain information may appear (such as the number of comments) and so on. There are three clear ‘types’ of Themes which are explained below. It’s important to understand the difference between configuration and customization in relation to Themes; configuration are generic options available whereas customization means tailoring the Theme to the clients requirements e.g. if you want a video background on a theme this may require specific coding (customization) for your needs as this functionality would unlikely be available as a default configuration option on a Theme.
Here then are the three categories/types of WordPress Themes:
Free WordPress Themes
These are generally GPL and don’t cost any money to use. They also often come with many configuration options such as the excellent and very powerful Constructor Theme. Free Themes usually suit bloggers and small businesses where the business owner has the skill and time to configure a free Theme.
Advantages: Free to download and use, there are thousands of free Themes available,
Disadvantages: Usually have a link in the footer to the Theme designer, not customized to specific Website requirements, often limited support, much time often required to configure free Themes.
Premium WordPress Themes
These Themes generally allow for configuration so that you may, to a degree, personalise your Theme for your purposes. Because the Theme is generic (i.e. the same Theme is sold to multiple people for multiple purposes) all specific requirements usually cannot be met. A compromise is therefore necessary with Premium Themes in that they usually offer more configuration options than free themes however may not suit your exact needs.
Advantages: Cost less than a Custom Theme, some great looking and functionality rich Themes available, often have good documentation and support.
Disadvantages: Not customized to specific Website requirements, time often required to configure Premium Themes, Usually not cost effective if customization is required.
Custom WordPress Themes
Custom Themes are made to fulfil specific requirements in relation to functionality and ‘look and feel’. Usually a graphic designer will design the look and feel in PhotoShop (or similar) and then a WordPress consultant will create the Theme from these images (usually PSD files). If branding and consistency of image are important then a Custom Theme is likely required.
Advantages: Usually supported better than premium Themes, tailored to exact requirements, consistency of brand and image, owned by the purchaser therefore often no license restrictions.
Disadvantages: Usually more expensive than Premium Themes (although less expensive than people think).
Combination WordPress Themes:
It is worth knowing that a free or Premium Theme may allow for child themes which also may be free, premium or even custom. For example, the excellent Theme Hybrid is free to use and has numerous free to use child themes. There are also premium child themes available for purchase and some WordPress consultants will make up a custom child theme for your purposes if required.
What category/type of Theme you choose depends mostly on your budget and requirements. Be aware however that it can be more costly and time consuming to manipulate a free or premium Theme to suit your needs rather than hiring a consultant to create a Custom WordPress Theme for you.