Speech Therapy focuses on Receptive and Expressive Language. In simple words it works on building the ability to understand spoken words and to use words to express oneself. It is broadly aimed at the following:
1. Children who are unable to speak as age appropriate
2. Adults who have lost their speech due to trauma/stroke etc.
Below is a brief overview of the conditions which may warrant speech therapy:
Autism: A variable neuro-developmental disorder characterised by impaired social interaction skills.
Misarticulation: Speech disorder where quality of spoken words is affected.
Stammering:  A disorder where fluency of speech is affected.
Cluttering: A communication disorder where the listener can't understand speech due to rapid rate of speech, erratic rhythm etc.
Cleft lip & Palate: Congenital anomaly where their is a deficit in development of the lip/oral cavity.
Aphasia: Can be motor or central, chiefly seen after stroke/ head injury.
Dysarthria: A kind of neuro-motor speech disorder.
Voice Disorder: resulting from vocal nodules, puberphonia etc.
Hearing Impairment: Speech pathology because of decreased aural stimulation.
Cochlear Implant Rehabilitation: Speech and language rehabilitation post a cochlear implant.