We have been creating Content Management Systems for web sites before Content Management Systems or CMS became such a huge buzzword.
What is a Content Management System?
A Content Management System is a tool that lets you manage the information on your web site without having to know anything about HTML or web development. Perhaps you'd like to change the text on your home page, add a press release, or update your client list. Use a Content Management System to manage all of the information that appears on your site, without having to bring in your web developer.
Why do you need a Content Management System?
To be honest you might not need a CMS. Some businesses have web sites with sections, navigation, content, etc. which do not require changes often. In these situations it may be more cost-effective to request a web developer to make a change for you when you need it rather than invest in a CMS that you may not use very often.
For those companies which have ever-changing content, it is essential that the website be updated DAILY. It has been shown that people who visit a website over and over again do so because the content is fresh and changes often. Would you go see the same movie at the same movie theater over and over again? No, but you would visit a theater often which offered the latest movies. This holds true for your website. If this is your business model, then you would benefit from an investment in a CMS where you can update your web site as often as you want.