"He walked toward the door."
"He walked towards the door."
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From this website
http://grammar.quickanddirtytips.com...s-towards.aspx
there is this explanation [quoted]:
"Toward" and "towards" are both correct and interchangeable: you can use either one because they mean the same thing. Many sources say the "s" is more common in Britain than in the United States, so you should take into account what the convention is in your country, and use "towards" in Britain and "toward" in the U.S.
This website
http://www.grammarly.com/answers/que...rd-or-towards/
offers a more thorough explanation.
Don