In "Information Architecture for the World Wide Web" (second edition, page 219), Lou Rosenfeld and Peter Morville write, "We define content broadly as 'the stuff in your Web site.' This may include documents, data, applications, e-services, images, audio and video files, personal Web pages, archived e-mail messages, and more. And we include future stuff as well as present stuff."
The type of content you produce influences the popularity and profitability of your website. People will subscribe to and read blogs that are well written and informative or entertaining.

If you operate a paid membership website, your content needs to be interactive and educational. Directly fulfilling user informational needs and providing channels for user feedback are important.Content goes a long way in establishing the value of your website for each visitor. It determines the amount of repeat visitors you’ll get and transforms your personal and business brand. It is easy for high quality content producers to receive natural citations and recommendations. I’m sure you all know how incredibly valuable word of mouth is for increasing sales and your audience reach.

On the web, there is no expiration date for good content. It can go out of date for some subjects. But as long as it resides somewhere on a server and is accessible from the web, you can reap the rewards in terms of readers forever.
Adding good content is the most important thing you need to do if you want to be found on the web. Even if your site is technically perfect for search engine robots, it won’t do you any good unless you also fill it with good content. Yes, really!
Good content to me is text that is factually and grammatically correct, though that is not necessarily a must for all kinds of sites. Whatever your site is about, the content needs to be unique and/or specific enough to appeal to people. More specifically, it needs to be useful to the people you want to find your site. Good content is key to website promotion success. All the bells and whistles in the world will not hold an audience like compelling information.