This is what I remember my speech therapist telling me: A stutter is characterized by disfluencies that make up 10% or more of your overall speech. 10% obviously being a very minor one. The range is pretty much 10% -85%. Everybody stutters from time to time, but you're not a stutterer unless your disfluencies make up at least 10% of your speech. Filler words such as "um," "like," "uh," and others are a little trickier. Stutterers typically use them to avoid stuttering, and the filler words become a part of their stuttering pattern (lol I used to say "uh" a lot, and it got so bad that if I tried to say, "I had a good weekend," for example, I would say, "I ha-uh-had-uh-h-uh-had a good weekend). People who don't stutter don't have this problem, they purely use them as filler words. Using filler words isn't characteristic of being a stutterer, it's when you use them to try to circumvent stuttering.