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Thanks for your kind comments about my adding on Islam to Tobacco smoking. If you have a chance, perhaps you can explain to me about how reverts work. Is it possible to revert sections of an article, not the whole article, using the prior history? Can undo be delimited to a section? Well, you don't have to bother with this... .  | Talk 

And thank you for your kind response and questions!  I'm always happy to help, it's never a bother!  Yes it is possible to undo or revert specific edits, or a series of edits in an article.  The new 'undo' button next to each edit in the 'history' tab of an article, can be used to try and undo that specific edit, it's success is dependent on there not being any conflicting intermediate edits between that particular edit and the current version of the article.  One can also go back to a previous version, by going to the article's history, and editing an old revision of the page. If you do this, any changes made since that revision will be removed.
Here are some links with more detail on this subject: Help:Reverting, WP:VANDAL, WP:Vandalproof.  Hope this helps!  –  † "