Um

Why, um, not to um.

Although we may not consciously realise it, in a two-person conversation, people speak by taking turns. When someone thinks it is their turn to talk, they do. Otherwise, they listen. A two-person conversation becomes like a tennis match. Inevitably there are short periods of silence as people pause to let the other person take over the speaking. But sometimes a speaker doesn’t want to give up their turn and instead wants a little extra time to think about what they’re going to say next. They use a ‘filler’ to signal this.