How to look at the changes to an article
Select...
  Article version selection  
...and compare!
  Differences between two page versions  

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.

Read more:
To add this auto-updating template to your user page, use {{totd}}
My Background
   
enThis user is a native speaker of the English language.
This user speaks several European languages.
This user is a scientist.
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This user is a social entrepreneur.
progLike one third of Wikipedians, this user is a programmer.
This user is old enough to remember what a typewriter is, and that's all you need to know.
My Interests
   
This user lives for
science!
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My Travel
   
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My Principles
   
This user thinks you can learn a lot by editing an encyclopedia.
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This user wants to see everything in its place.
?This user believes
that common sense is
an uncommon commodity.
KThis user uses the Kelvin scale, because 0K is much cooler than
−273.15°C or −459.67°F.