Hi, My name is Ed. Retired from the Navy and from aerospace engineering. I have been "dabbling" with the pages of book authors that I have in my home library collection. I use the Library of Congress, Abebooks, Amazon, publisher sites and anything else that comes to mind for correct information. I am a total novice at this but enjoy the clean-up and creation activity. In particular, I have been listing ISBN's for initial book releases. This information is important to book collectors in locating 1st editions. Software is available to load a large amount of data into a database with a simple hand scanner. So, I am trying to learn more about cataloging books. Spent a ton of time correcting "invalid ISBN's". Great experience in dealing with a wide range of subject matter.
In the page history for any page, click (prev) (#9 on the image top right—click on the image to see a larger version) to see the changes for any version from the one just before it. To compare a series of versions, just click any two radio-buttons to select the set of versions, then click the Compare selected versions button (this only works if you have JavaScript enabled).
You should be presented with a screen that shows you which words have been removed and which ones have been added (affected words are highlighted in red). You always can revert to an earlier version by selecting it from the history, editing and saving it. We call these "diffs" because the URL has the word "diff" in it. Diff is short for difference.
