Why when I edit a post does it show up in the Edit history ...

[spin]

as an unexplained edit?

I add an explanation in italics for why I edited the post but obviously I am missing something. I have also noticed that this happens on other posts that were edited.

I will edit this post as an example.

edited this post to add ...

It's not a big deal, just curious.

[Kali]

1. there is a separate box for adding an explanation below the main message area when you are editing

I wrote the edit message in the "explain edits" box/line"
click on my edit history

last edit and I will not add any explanation in the box

[Make7]

2. There is a text field below the Message text field...

... titled Explain edits. (It's right above the Check Spelling, Preview and Update my post buttons).

Any text entered there is what is displayed as the explanation for the edit - not any text you update in your post.

Here is an example of explanations of what I did to one of my posts when editing:

http://www.democraticunderground.com/?com=view_post&forum=1240&pid=25018#edits

[spin]

3. Thanks for your support. (n/t)