Under the new scheme of service tax all the activities that are covered by the definition of service as stated in 65 are taxable services.
In order to provide relief to public at large the government has declared a certain set of services which are exempt from service tax law.The list is stated in sec 66d of the service tax law and is known as negative list.
There are also certain activities where there is confusion regarding the nature of activity ,i.e., whether they are service or not.In order to remove the confusion,the government has declared a certain list of activities as services in sec 66e.These are the declared servies.
you can refer to page 39-41 of the following http://servicetax.gov.in/st-act-ason24oct2013.pdf Regards