Infants, around 2 months and older, often coo with actual gurgles by vibrating spit in their mouths and throats initially before progressing to string basic vowels (“ah,” “eh,” “oh”) together. The first consonant sounds are usually repetitive jabbering of "m" and "b" so sounds such as "mmm-mmm-mah-mamamama" and "bah-bababa" are usually learned much earlier than recognizable words.
It isn't until around age 1 that the baby develops the knowledge to not repeat the sound as repetitively, learning to simply say, "Mamam," "Dada," and "Baba."
By age 2 children typically have left the repetitive nature in words and fully say Mommy or Daddy.
Speech Impediments (Weally?!)
By age 3 then children usually speak relatively clearly and are understood by family members. Speech impediments are reduce to only one, possibly two, and can usually be corrected by the child when pointed. What is most frequently observed is that children often get syllables mixed up for specific words (often it's something that excited them when they originally learned the word) and, for example, say "disodaur" instead of "dinosaur" frequently but can be corrected to say it the proper way when brought to their attention.
More often than an impediment that distorts words though, very young children often use a lot of interjectory words like "uh" and "um" while not keep cohesiveness in speech pattern (sometimes speaking rapidly, abruptly ending sentences with no pause between the next, repeating the same idea/thought multiple times within the same few sentences).
By age 4 the speech impediments become much more rarer and parents of children who have issues being understood clearly by others may be encouraged to enroll their child into a speech therapy course. Sentences are still short but strung together much better and, of course, vocabulary is expanding rapidly.
So, generally by age 4 and 5 children speak in compound sentences and should be clearly understood well by strangers. Speech impediments are not common after this age unless the person has a learning disability, physical limitation to overcome, or has been, at least, verbally neglected.
Ultimately...if woo chooss to b typin wike diss den yer weally prah-bee unda 3 yeas oll! Hewwo!
Much more often than a constant speech impediment, young children may omit letters from words or use what they know of one word and apply it to another word.
A good example of this would be the word "sleepy". If the child is mispronouncing "sleepy" they are liking to be saying "sheepy" since it goes along with other words (sheep, she, shoes, shirt, share, show) they are also learning or "seepy" by outright omitting the "l" in the word. Both "seepy" and "sheepy" would be much more commonly seen than something like "sweepy" since "sweep" would be learned from an action (more difficult for young children to grasp) and "sw" doesn't frequently come up in language with children. A sheep may be something the child has seen before in picture books, and "sh" occurs frequently when adults speak to children.
Children are going to try to relate a new word by comparing it to a word or words that they already know and recognize.
An example of this could be a child misunderstanding the word combination for "tummy ache" and saying it as "tummy egg" instead. The child would have likely learned "egg" before "ache" since "egg" may be in their diets as well as being tangible compared to an abstract feeling such as "ache".
M-most people d-don't talk like th-this when they st-stutter from n-nerves or bashfulness.
It's more...it's more like...going back and...and starting over or...or...hesitating. Maybe they are repeating...repeating some...some words and m-m-m-maybe repeating sounds many times in a row before finishing a word if th-th-th-the stutter isn't necessarily due to just nervousness. Sometimes people with stutters actually have to start their...sometimes people with stutters actually have to start their entire sentence over from the beginning.
Stuttering in thoughts is a lot more fluid than in speech because there's no physical connection that needs to be made between thought and actual speech. So, nonverbal stuttering should never appear like th-this but more like...like...well, like this.
Up until around age 3 children learn primarily concrete words, or, basically, words that you can associate with a physical item or thing (generally tangible). By age 3, children are likely able to learn these concrete words without the need for a visual reference, so word learning tends to accelerate around this age.
Some words, often emotional or abstract in nature, are often misused by children younger than 5 years old. They may frequently misuse words such as love or say things they don't understanding the meaning of when saying them to someone else. Since emotions are difficult to grasp, children under 5 usually focus more on items and things instead.
Typical Sentence Structure
Initial sentences are of only up to three words, but by age 2 the child generally expands the thoughts to four or five full words. Speech develops rapidly though and by 3 years old children children are forming more coherent, actual sentences versus two-word combinations.
So, a child under 2 may say, "Mommy chair," meaning, "That's my Mommy's chair," or, "Eat food," to alert their caregiver that they want some food to eat.
Between 2 and 3 the child begins to understand and grasp the idea of "I", "me", "my", "mine" and uses those frequently. So, a slightly longer, more-understandable sentence structure develops. "That my ball!"
Generally, by age 3 the child has stopped speaking in such brief, brief two or three word sentences to get their point across and speaks more fluidly in complete, but still somewhat short, sentences. Children begin saying sentences such as, "I want to get my ball now," or "Let's go get my ball."
It's common for a child under 3 to mix words up, get confused, mispronounce first-letter-of-words sounds ("weally" being more realistic then than "weawwy"), and even make up words that they've never heard you use. By 3 though, this is usually resolved and by 4 if it continued, again, it would indicate that something else may be an issue for the child (learning challenge, physical challenge, abuse, neglect).
So, by age 4 or 5 children are speaking with much more complexity and even using compounding sentence to convey multiple thoughts or objectives within the same sentence. You can start to see things like, "I want to go get my ball and play catch!" become, "I want to go get my green ball now and then we can play catch outside!" and more and more complex and thought-out quite quickly.