When we speak in a forum where several ears are tuned towards us, the words may not come as quickly as we would like. We try to fill the gap by using words like um or and or some other word in your phrasology that gives you comfort.
There could be various reasons ranging from the power that comes from breathing or the preparation that goes into the presentation. The end result is your speech or presentation ends up being ineffective, and the audience could very well stop going to your seminars from that point on.
How can you stop using the filler words? The London Speaker Bureau has published an infographic that gives you eleven ways of avoiding saying um or your favorite fillers.