Language has to do with meanings, rather than sounds. A language disorder refers to an impaired ability to understand and/or use words in context.
A child may have an expressive language disorder (difficulty in expressing ideas or needs), a receptive language disorder (difficulty in understanding what others are saying), or a mixed language disorder (which involves both).

Some characteristics of language disorders include:

• improper use of words and their meanings,
• inability to express ideas,
• inappropriate grammatical patterns,
• reduced vocabulary, and
• inability to follow directions.

Children may hear or see a word but not be able to understand its meaning. They may have trouble getting others to understand what they are trying to communicate. These symptoms can easily be mistaken for other disabilities such as autism or learning disabilities, so it is very important to ensure that the child receives a thorough evaluation by a certified speech-language pathologist.

Language is different from speech.

Language is made up of socially shared rules that include the following :
1. What words mean (e.g., "star" can refer to a bright object in the night sky or a celebrity)
2. How to make new words (e.g., friend, friendly, unfriendly)
3. How to put words together (e.g., "Peg walked to the new store" rather than "Peg walk store new")
4. What word combinations are best in what situations ("Would you mind moving your foot?" could quickly change to "Get off my foot, please!" if the first request did not produce results).
Speech is the verbal means of communicating. Speech consists of the following: The characteristics of speech or language impairments will vary depending upon the type of impairment involved. There may also be a combination of several problems.

Articulation

When a child has an articulation disorder, he or she has difficulty making certain sounds. These sounds may be left off, added, changed, or distorted, which makes it hard for people to understand the child.
Leaving out or changing certain sounds is common when young children are learning to talk, of course. A good example of this is saying “wabbit” for “rabbit.” The incorrect articulation isn’t necessarily a cause for concern unless it continues past the age where children are expected to produce such sounds correctly.
Fluency refers to the flow of speech. A fluency disorder means that something is disrupting the rhythmic and forward flow of speech—usually, a stutter. As a result, the child’s speech contains an “abnormal number of repetitions, hesitations, prolongations, or disturbances. Tension may also be seen in the face, neck, shoulders, or fists.”
Voice is the sound that’s produced when air from the lungs pushes through the voice box in the throat (also called the larnyx), making the vocal folds within vibrate. From there, the sound generated travels up through the spaces of the throat, nose, and mouth, and emerges as our “voice.” A voice disorder involves problems with the pitch, loudness, resonance, or quality of the voice. The voice may be hoarse, raspy, or harsh. For some, it may sound quite nasal; others might seem as if they are “stuffed up.” People with voice problems often notice changes in pitch, loss of voice, loss of endurance, and sometimes a sharp or dull pain associated with voice use.

A speech and language assessment should be conducted prior to a diagnosis or entry into therapy or program is made. The assessment is the foundation by which the professionals will base their therapeutic and treatment approach. An assessment is often done by a SLP and will consist of meeting the child, playing with developmentally appropriate toys, and listening to the child’s sound system. Standardized tests can also be used and typically look at at least five domains :

• Cognitive
• Expressive communication
• Receptive communication
• Gross motor
• Fine motor