Embolalia is automatic speech. Verbalization that occurs without conscious effort, such as repetitions and filler words.It refers to hesitation forms in speech, such as um, hmm, you know, like, okay, and uh.

Deriving from two Greek words meaning "something thrown in", as in the Greek emballein, from em, in, and ballein, to throw in or at.

According to Phil Cousineau, in his book "The Painted Word: A Treasure Chest of Remarkable Words and Their Origins": "The nervous, I mean, stammering habit of, you know, inserting, I mean kinda throwing meaningless words into, you know, a sentence, when you're, ah, talking. So embolalia describes the habit of throwing around words without thinking .The habit is characterized by often uncontrollable utterances (hmm, umm, errr), and is a nervous tic in languages everywhere".

Caused perhaps by a general deterioration or lack of respect of the spoken word, sheer nervousness, or a disdain for proper, poetic, or colorful use of language.

Public speaking coaches will tell you that it's OK to say 'uh' or 'um' once in a while, but the prevailing wisdom is that you should avoid them entirely. It's thought that they make speakers appear unprepared, unconfident, stupid, or anxious.

The idea of speaking without these filler words is actually fairly recent, and very American. It didn't emerge as a cultural standard until the early 20th century, when the phonograph and radio suddenly held up all the quirks that before had flitted by.

More Info: en.wiktionary.org