Many people use Twitter as a kind of new-age radio, getting the latest information about everything from transportation delays and retailing promotions to news about various industries by tracking the Twitter accounts of trusted sources, including news agencies, analysts and companies or their executives.
We are not going to start, with a calculator and an adding machine, tracking down what people received from other sources, other funds, other help from relatives, savings.
Indoor tracking systems which process data from one or more sources of location information to estimate where a person or object is located are not new.