A fallacy is a common error in reasoning which people (even well educated, careful people) often fail to notice in their own arguments or which devious people might use in their arguments in the hope that we won't notice them.
The Straw Man Fallacy
Example: People who think abortion should be banned have no respect for the rights of women. They treat them as nothing but baby-making machines. That's wrong. Women must have the right to choose.This argument commits the straw man fallacy. It misrepresents the position of the opposing side in such a way that the opposing position appears obviously false or ridiculous. (That is, it creates a 'straw man' just so it can be knocked down.) It's worth noting that 'straw manning' often takes place on both sides of charged debates like the one concerning abortion. Consider a claim like: 'People who are in favour of abortion think it's okay to commit cold blooded murder.'
'Strawmanning' your opponent can be an effective strategy in an argument. If your audience doesn't realize that's what you're doing, you may succeed in convincing them that your opponent's view is wrong. However, it's an intellectually dishonest strategy & so not useful for getting at the truth about things.
The moral: Strawmanning your opponent is bad. Don't do it.