Bethesda is a census-designated place in southern Montgomery County, Maryland, just northwest of the United States capital of Washington, D.C. It takes its name from a local church, the Bethesda Meeting House (1820, rebuilt 1849), which in turn took its name from Jerusalem's Pool of Bethesda. (In Aramaic, ܒܝܬ ܚܣܕܐ beth ḥesda means "House of Mercy" and in Hebrew, בית חסד "beit ḥesed" means "House of Kindness".) The National Institutes of Health main campus and the Walter Reed National Military Medical Center are in Bethesda, as are a number of corporate and government headquarters.
Bethesda is one of the most affluent and highly educated communities in the United States. In 2014 it placed first in Forbes list of America's most educated small towns and first on CNNMoney.com's list of top-earning American towns in 2012. In April 2009, Forbes ranked Bethesda second on its list of "America's Most Livable Cities." In October 2009, based on education, income, health, and fitness, Total Beauty ranked Bethesda first on its list of the U.S.'s "Top 10 Hottest-Guy Cities."
As an unincorporated area, Bethesda has no official boundaries. The United States Census Bureau defines a census-designated place named Bethesda whose center is located at . The United States Geological Survey has defined Bethesda as an area whose center is at , slightly different from the Census Bureau's definition. Other definitions are used by the Bethesda Urban Planning District, the United States Postal Service (which defines Bethesda to comprise the zip codes 20810, 20811, 20813, 20814, 20815, 20816, and 20817), and other organizations. According to estimates released by the U.S. Census Bureau in 2013, the community had a total population of 63,374. Most of Bethesda's residents are in Maryland Legislative District 16.