What do you mean by underwriting insurance ?

Underwriting in insurance mean that the process of assessing , evaluating and rating of the risks  and  then finalized by issuing of the insurance policies or contracts . This is mainly the underwriters and underwriting department concerns and job.However the underwriter to  accomplish this job accurately sometimes and in particular in regard to the substantial risks may need assistance of specialized surveyor.

My best wishes. 

Please also specify the premium calculation details.