Various consultants offer advice in management , accountancy , the environment , entertainment , technology , law ( tax law , in particular ) , human resources , marketing , emergency management , food production , medicine , finance , statistics , software , life management , economics , public affairs , communication , engineering , sound system design , graphic design , or waste management . A consultant ( from `` to discuss '' ) is a professional who provides professional or expert advice in a particular area such as management , accountancy , the environment , entertainment , technology , law ( tax law , in particular ) , human resources , marketing , emergency management , food production , medicine , finance , life management , economics , public affairs , communication , engineering , sound system design , graphic design , or waste management .