What is a Content Management System (CMS)?A Content Management System is a website admin ("back-end") system comprising a collection of web forms and pages which let you update a website without having to know how to code in HTML or understand the technical issues of website design.
So you can update the content (pages, text, images, videos etc) of a website in the CMS utilising various template page types, eg news page, normal content page, photo gallery etc. The CMS is linked to a database which saves all the data (text, images etc) and metadata (details of when a page was updated, who edited it, etc).
The "front-end" of a website controlled by a CMS uses stylesheets to ensure consistency of presentation across the site, no matter who created or updated the pages, and to ensure that pages will display properly on different devices and to disabled users. So your Headings and text will always be navy Arial font (or whatever), even if someone in the Planning department has a penchant for purple and Comic Sans MS!
There is usually some choice over the "look and feel" of the page templates, and there should be some choice around the layout of the pages and the site structure (what goes where). A CMS will often include "add-ons" or "plugins" such as Shopping Carts or Forums which you can add to your site, depending on the CMS you use.
Why use a CMS?A CMS is particularly useful in a large organisation where more than one person needs to create and update the web pages - especially if these are to be "subject experts" who are non-technical. It can also be useful even to technical users as it ensures consistency on a large site.
It can also be useful even in a smaller organisation if there is no Web Designer on the staff and the site was created by a Freelancer such as myself - the CMS will allow the staff to update the website themselves without having to learn HTML or buy tools such as Adobe Contribute, and without having to ask the Freelancer every time a typo needs fixed or a price needs updated.
When not to use a CMSSometimes a CMS is 'overkill' or will be a waste of money for a client.
For example, if you only need your website updated once a year (eg an updated pricelist) it’s probably more cost-effective to pay your local friendly Freelancer for an hour or so of work than to pay for a CMS and training that staff will probably forget since they don’t use the system that often.
What CMS should I use?This is a harder question to answer, as it depends very much on what your website is and what you want to do with it.
WordPress, Joomla and Drupal are 'free' Content Management Systems which are popular and widely-used, with various add-ons available. For a smallish website with standard requirements which will fit within the available templates one of these may be a good choice.
I have worked on 3 different Content Management System products which were purchased by the organisations I worked for. These gave much more choice over the customisation and layout, as the templates were designed specifically for the organisation. They were used by large numbers of non-technical members of staff and needed to be robust and reliable. But there was obviously a cost implication which puts such a system outside of the budget of most SMEs.
Another option is a mini-CMS written by your Web Developer, which will let you edit certain parts of certain pages that you need to update regularly, using bespoke web forms and a small database. This is a cost-effective solution that I've successfully employed for a number of clients, so if you think this is what you need, please let me know!