Digital Realty owns and operates over 200 data centers worldwide. It has more than 30 million rentable square feet and over 2,300 customers. Digital's offerings range from retail co-location, where an enterprise may rent a single cabinet and rely on Digital to provide all the accommodations, to "cold shells," where hyperscale cloud service providers can simply rent much, or all, of a barren, power-connected building. In recent years, Digital Realty has de-emphasized cold shells and now primarily provides higher-level service to tenants, which outsource their related IT needs to Digital. Digital Realty has also moved more into the co-location business, increasingly serving enterprises with smaller space and power needs. Digital Realty operates as a real estate investment trust, or REIT.