As the use of electronic information sources becomes increasingly common, the need for understanding their use becomes critical. This paper describes what usage statistics of electronic materials entail, how they can be used for a variety of library decision making, and the process in which the data can be best acquired, processed, analyzed and presented. It also offers a general introduction to on-going standardization efforts related to usage statistics of electronic resources and services. Some of the research opportunities that these newly developed data sources present to library and information science field are identified.