In one sense, all the content on a website is related. At least, it should be.
If you sell coffee, all of your content will relate to coffee, in one way or another. If you sell garden furniture, all your content will relate to gardens and furniture.
But that’s not what I want to talk about.
What I’m suggesting is that you create a series of streams of content that are much more closely related.
For example, if you sell or write about coffee makers, you might create a series of content pages which focus on all the different brands and models of single serve coffee makers. That’s a subset of the coffee topic, but gives you enough raw material to create a series of 5 to 10 pages of content.