The disorders are a group of disorders in which people experience significant physical symptoms for which there is no apparent organic cause.

Explanation:

A person having somatic symptom disorder focuses more on physical symptoms such as weakness, pain or shortness of breath and it results in problems functioning or distress.

The person gets excessive feelings an thoughts about the physical symptoms which may or may not be related to a diagnosed medical condition but the person experiences the symptoms and believes it that he is sick.

A person cannot be diagnosed with this disorder only because the medical cause cannot be identified for the physical symptom but because of the the excessive thoughts, behaviours and feeling related to illness.