Filler words are the demons that creep into our sentences in the form of unnecessary words or sounds, without us noticing them.
Although filler words don’t add any meaning to our statements, they allow us a break to think about what we’re going to say next. This also means, they let our audience know that we’re haven’t finished speaking yet.
Having said that, fillers can easily be replaced with a (real) pause because they often distract our audience.
Below are some more reasons for not using filler words 
Thoughts?
Which of these do you use or hear the most?
