Fillers (sometimes called discourse markers) are words or sounds like erm, er, you know, like, well, I mean etc used in spoken discourse to fulfil various functions. They may eg :
- give the speaker thinking time while avoiding frequent or long pauses. Example : It was erm, like as if he wanted to tell us about it but, you know, wasn't sure what to say
- serve as a turn taking strategy to indicate the speaker wants to take the floor. Example : Erm - could I just add something?
- be used as a politeness strategy , indicating hesitation before giving a dispreferred second in an adjacency pair - ie a refusal of a request or invitation : Example A : Would you like to come to dinner on Saturday? B : Oh, erm well, I'd love to but ....