There are many different challenges children (and adults) could have with communication. Below are some of the common communication disorders addressed in the schools. A child may have more than one area of difficulty.
Language Disorders
Language disorders generally fall into two broad categories: Receptive and Expressive. Receptive language is your child's ability to listen and understand. Receptive language tasks include pointing to pictures to respond when asked questions, following directions, etc. Expressive language is your child's ability to speak and express themselves using words. Expressive language tasks include producing grammatically correct sentences to express thoughts and ideas, story telling, etc.
Children can have difficulties in neither, one, or both of these areas.
Articulation Disorders
Articulation disorders are the inability to produce age and culturally appropriate speech sounds. Some students may not be able to say the "R" even though English is their only language or their first language and English both have "R." Phonological disorders also involve speech sounds. Students may apply certain patterns to their speech, such as omitting the final sound of words. This may be cause for concern if their native language does have consonants at the end of words and they are over a certain age. Certain patterns are developmentally appropriate. For more information, see the Language Development section.
Voice Disorders
Voice disorders involve the quality of an individual's voice. They can include abnormalities in volume, rate, and quality (hoarseness, etc.).
Fluency Disorders
Fluency disorders involve an individual not being able to speak smoothly. They may have many dysfluencies (a.k.a. stuttering). Dysfluencies can include repetitions (p-p-p-pizza), blocks (inability to get a word out despite knowing what they want to say), and prolongations (Fffffffor...). (Note: this can be developmentally appropriate for a certain age range. See the Language Development section for more information.)
Pragmatics Disorders/Difficulties
The term pragmatics refers to the use of social skills in communication. Pragmatic skills include (but are not limited to) maintaining conversations, taking turns, maintaining eye contact, maintaining appropriate distances from others while speaking, social problem solving, social rituals (e.g. "please" and "thank you"), understanding and use of figurative language, etc. Pragmatics difficulties may be included as part of "Language Disorders."
Please note that many of these difficulties could occur in any combination. They can also occur secondary to a primary disability, such as cleft palate or Autism.