I have a hard time describing Idea Knot in words. So I'll try to talk through how I show people how I use it because that does click. I think a comment on this page best describes how I use it to "re-use relevant ideas in different combinations."
Idea Knot has groups (think tags), ideas (think note title), and notes. An idea can belong to more than one group, so it's not a strict hierarchical note application like so many others; this is very free-form.
The manual has an example of using Idea Knot for boilerplate text for form letters. That got me started! I dis-assembled a large number of my shell scripts for work for Idea Knot. For instance, I have a group called Basics, with the ideas "skeleton - header," "skeleton - variables," "skeleton - parameters," "basic flags - parameters," "basic flags - pre-body," "skeleton - main," "read from file," and "skeleton - footer." I have other groups for the major types of scripts I write. So when I want a Spectrum script to collect a list of Cisco serial numbers (this is not hypothetical), I create a new group for it. Then I flip through the other groups, like Basics and Spectrum, and drag ideas to the new group. When I go back to the new group, I can re-order the ideas, hit the button for the Combined View, and voilà! I have 90% of a new Spectrum shell script already done. This has saved me hours at work, no kidding. (Now if I had a tool that would read metadata to determine the order, like all variables go in one block, all parameters in the next and so on, I wouldn't even have to re-order the ideas in the new group. Or at least not as much.)
So form letters, code skeletons, and notes that need to be in multiple "folders" (aka tags not hierarchy), that's Idea Knot. If it still doesn't make sense, try reading the manual in the download since it's probably more clear than I am.