This is a long post so I think I have to split it between comments. I'd disagree and say there are clear definitions and categorizations of what stuttering is. Admittedly, there is a major lack of education on fluency for SLPs which hopefully will begin to change as we study and more information. Sadly, there is not much focus on it because it a low prevalence disorder (I know therapists who have been practicing for 10+ years and never had a stuttering patient). That being said, a lack of education does not mean a lack of evidence. There are different types of stuttering (neurogenic, psychogenic, developmental). For the sake of this conversation, I am talking about persistent developmental stuttering that happens in childhood and progresses to adulthood. I will preface by saying that if I misunderstand or did not answer your questions how you intended it, then please let me know and I am happy to reclarify or continue discussing it! It is a bit harder answering in limited space online. I am also happy to do some research and get back to you on any specific thing if you'd like. **What is stuttering?**  Clinically, stuttering is defined as a speech disorder characterized by involuntary disruptions in speech that are typically repetition of sounds, syllables, or words; prolongation of sounds; and interruptions in speech known as blocks (that are atypical disfluencies as well but those are more uncommon). Children who stutter consistently for 6 months or more can be evaluated for persistent developmental stuttering. Beyond early elementary years (typically ages 6-8), if a child still stutters then they will often be a lifelong stutterer. There also clinical rating scales that can be used to classify mild, moderate and severe stuttering based on frequency of stuttering and effect on quality of life (also a standardized evaluation that has been created and tested). There are obviously exceptions to every rule because people are not all the same. **What is and isn't learned in stuttering?** Stuttering is described into primary and secondary behaviors. Primary is the actual speech errors (prolongation, blocks and repetitions) and these are not learned behaviors. Secondary behaviors are accompanied physical movements that are usually learned and can also be called avoidance behaviors. These include things like excessive limb movements, irregular head movement/muscle twitching, etc