People who have broken legs use crutches. Writers who have broken sentences use crutch words.
A crutch word is an empty word with no purpose. It’s just a filler. Dandelion fluff. If you remove it from your sentence, you won’t even notice. No one likes to hear someone fill their speech with these. No one will like to read them either. They weaken your writing dramatically.
“Um” is the best example. Here are a few more. You can find lots of lists of these all over the web.
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