Equity Residential is a real estate investment trust. The Company is focused on the acquisition, development and management of apartment properties in various markets of the United States. The Company's segments include Boston, New York, San Francisco, Seattle, Southern California, Washington D.C., Non-core - South Florida, Non-core - Denver, and Non-core - other. ERP Operating Limited Partnership (Operating Partnership) conducts the multifamily residential property business of the Company. The Company's property ownership, development and related business operations are conducted through the Operating Partnership. The Company holds interests in approximately 390 properties located in over 10 states and the District of Columbia, consisting of approximately 109,650 apartment units. Its properties are of various building types, such as garden, mid/high-rise and military housing. Its core properties are located in New York, Los Angeles, Boston, Seattle and San Diego, among others.