A basic straw man fallacy is meant to distract and deceive by using a twisted version of the opposing side’s argument against them. Users of this form of propaganda build a “straw man” and attack it in place of their opponent’s actual argument.
The straw man will undoubtedly be a weaker, often times extreme, version of the original argument, similar in appearance but much easier to refute and destroy.
Here’s an example:
Person A: Our children are gaining too much weight. We need to limit the amount of junk food they’re given in schools.
Person B: So you propose we let our students starve?
Wikipedia presents a more sophisticated example:
Person A: We should liberalize the laws on beer.
Person B: No, any society with unrestricted access to intoxicants loses its work ethic and goes only for immediate gratification.
If you are presented with a straw man argument, it is very simple to refute it by either pointing out the straw man, clarifying your original argument, or dismissing the straw man argument by unveiling its fallacies (basically, successfully arguing against the straw man, although this can in fact play into your opponent’s attempt to divert the argument).
For more information on the straw man fallacy, take a look at the following resources: