For as long as we’ve had language, some people have tried to control it. And some of the most frequent targets  of this communication regulation are the ums, ers, and likes  that pepper our conversations. Ancient Greek and Latin texts warned against speaking with hesitation, modern schools have tried  to ban the offending terms, and renowned linguist Noam Chomsky dismissed these expressions as “errors” irrelevant to language. Historically, these speech components had been lumped into the broader bucket of “disfluencies”— linguistic fillers which distract  from useful speech. However, none of this controversy has made these so-called disfluencies less common. They continue to occur roughly  2 to 3 times per minute in natural speech. And different versions of them can be found in almost every language, including sign language. So are ums and uhs  just a habit we can’t break? Or is there more to them than meets the ear? To answer this question, it helps  to compare these speech components to other words we use in everyday life. While a written word might have multiple definitions, we can usually determine its intended meaning through context. In speech however, a word can take on additional layers of meaning. Tone of voice,  the relationship between speakers, and expectations of where  a conversation will go can imbue even words that seem like filler with vital information. This is where “um” and “uh” come in. Or “eh” and “ehm,” “tutoa” and “öö,” “eto” and “ano.” Linguists call these filled pauses, which are a kind of hesitation phenomenon. And these seemingly  insignificant interruptions are actually quite meaningful  in spoken communication. For example, while a silent pause might be interpreted as a sign for others to start speaking, a filled pause can signal that you’re not finished yet. Hesitation phenomena can buy time for your speech to catch up with your thoughts, or to fish out the right word  for a situation. And they don’t just benefit the speaker— a filled pause lets your listeners know an important word is on the way. Linguists have even found  that people are more likely to remember a word  if it comes after a hesitation. Hesitation phenomena  aren’t the only parts of speech that take on new meaning during dialogue. Words and phrases such as “like,”  “well” or “you know” function as discourse markers, ignoring their literal meaning to convey  something about the sentence in which they appear. Discourse markers direct  the flow of conversation, and some studies suggest  that conscientious speakers use more of these phrases to ensure  everyone is being heard and understood. For example, starting a sentence  with “Look...” can indicate your attitude and help  you gauge the listener’s agreement. “I mean” can signal that you’re about to elaborate on something. And the dreaded “like”  can perform many functions, such as establishing a loose connection between thoughts, or introducing someone else's words or actions. These markers give people a real-time view into your thought process and help listeners follow, interpret,  and predict what you’re trying to say. Discourse markers and hesitation phenomena aren’t just useful  for understanding language— they help us learn it too. In 2011, a study showed toddlers  common and uncommon objects alongside a recording referring  to one of the items. When a later recording asked them  to identify the uncommon object, toddlers performed better if that  instruction contained a filled pause. This may mean that filled pauses  cue toddlers to expect novel words, and help them connect new words to new objects. For adolescents and adults  learning a second language, filled pauses smooth out awkward  early conversations. And once they’re more confident, the second-language learner can signal their newfound fluency by using the appropriate  hesitation phenomenon. Because, contrary to popular belief, the use of filled pauses doesn't decrease with mastery of a language. Just because hesitation phenomena and discourse markers are a natural part of communication  doesn’t mean they’re always appropriate. Outside of writing dialogue, they serve  no purpose in most formal writing. And in some contexts, the stigma these social cues carry can work against the speaker. But in most conversations,  these seemingly senseless sounds can convey a world of meaning.