When editing an article, there's a box named "Summary" underneath the article text. Unsurprisingly, the purpose of this box is to provide a summary of the changes you made in this revision.
I have seen many, many people using this ways that I find mildly problematic. I'd like to highlight a few of these and explain why I think they're problematic, in the hopes that people might start using the field more optimally.
If you're someone who has done one of these things, please don't feel attacked or criticized; I think just about everybody does it, and I know I have as well at times. Clearly nobody is going to be "perfect", including myself, in the past or going forward. This is simply an explanation for how we can do better, and why, to make people aware.
Dittoing edits from other articlesIt's very common for a kind of change to be made to many articles in a row. Sometimes, you'll see the same edit summary copy-and-pasted to all of them. Other times, only the first (or first few) messages get that summary; subsequent articles get "ditto" or "same" or some other message copy-and-pasted in.
When someone comes back a year later and views the edit history for one of those articles, "ditto" tells them absolutely nothing. Or worse, they might think you're dittoing the previous change
in that article's history, which is completely wrong.
So instead, it's better to copy-and-paste your edit summary to all of the articles.
Referencing other editsThis is very similar to the above. Someone will make a change on an article. Then they'll make a related change in another article--or someone else will make a related change in another article--and they'll say something that references those other changes.
These kinds of comments work in the context of the Recent Changes page. Unfortunately, they lose context in the edit history and will leave people scratching their heads in confusion later. Make sure your edit summary stands on its own!
Asking a questionA typical scenario: Someone will make a change, perhaps they'll fix the spelling of "enhancement". And while they're at it, something will catch their eye that they are curious about. Perhaps there was a bug noted ten issues ago. So they'll make their edit summary "Is __ bug fixed yet?".
That edit summary has absolutely nothing to do with the change that was made, which is bad enough. But what's even worse is, there's no obvious way to respond! The "Recent Changes" page is not a chat board. If you have a question, post it separately to the page's talk page. That'll make it possible for people to respond. It'll also prevent your question from vanishing permanently from view, which means that if it doesn't get addressed within the next few days, maybe it'll at least get noticed later, eventually.
SummaryIn short, the recommendation I'm trying to make is this: Write your edit summaries so that they'll be useful in the edit history. Forget about the Recent Changes list when writing summaries. If your edit summary is useful for the edit history, it'll also be useful in the Recent Changes list.
While it's not the most important of things, it is one of those things that does add up over time. And it will pay off later when you or someone else needs to dig through an article's history.
That said, the changes you're making to the article are much, much more important. Never let the "summary" field stop you from editing. A good edit with an empty or misleading edit summary is much better than no edit at all!