Formerly one of Germany's most important coal and steel centers and historically linked to the centuries-old Krupp family iron works, the city has developed a strong tertiary sector of industry and (sometimes together with nearby Düsseldorf) claims to be the "desk of the Ruhr area". It is home to 13 of the 100 largest German corporations and seat to several of the region's authorities.

In 1958, the city was chosen to serve as the seat to a Roman Catholic diocese (often referred to as Ruhrbistum or diocese of the Ruhr). In early 2003, the universities of Essen and the nearby city of Duisburg (both established in 1972) were merged into the University of Duisburg-Essen with campuses in both cities and a university hospital in Essen.

Essen is located in the center of the Ruhr Area, one of the largest urban areas in Europe, comprising 11 independent cities and 4 districts with some 5.3 million inhabitants. The city limits of Essen itself are 87 km (54 mi) long and border 10 cities, 5 of them independent and 5 kreisangehörig (i.e., belonging to a district), with a total population of approximately 1.4 million.

The city extends over 21 km (13 mi) from north to south and 17 km (11 mi) from west to east, mainly north of the Ruhr River, which forms the Lake Baldeney reservoir in the boroughs of Fischlaken, Kupferdreh, Heisingen and Werden. The lake, a popular recreational area, dates from 1931-1933, when some thousands of unemployed coal miners dredged it with primitive tools for the Reichsarbeitsdienst. Generally, large areas south of the Ruhr River (including the suburbs of Schuir and Kettwig) are quite green and are often used as examples of rural structures in the otherwise relatively densely populated central Ruhr Area.

The lowest point can be found in the northern borough of Karnap at 26.5 m (86.9 ft), the highest point in the borough of Heidhausen (202.5 m/664 ft). The average elevation is 116 m (381 ft).

Essen comprises 50 boroughs which in turn are grouped into nine suburban districts (called Stadtbezirke) often named after the most important boroughs. Each Stadtbezirk is assigned a Roman numeral and has a local body of nineteen members with limited authority. Most of the boroughs were originally independent municipalities but were gradually annexed from 1901 to 1975. This long-lasting process of annexation has led to a strong identification of the population with "their" boroughs or districts and to a rare peculiarity: The borough of Kettwig, located south of the Ruhr River, and which was not annex until 1975, has its own area code. Additionally (allegedly due to relatively high church tax incomes), the Archbishop of Cologne managed to keep Kettwig directly subject to the Archdiocese of Cologne, whereas all other boroughs of Essen and some neighboring cities constitute the Diocese of Essen.

The average temperature is 9.6 °C (49 °F), the average annual precipitation 829 millimetres (33 in). The coldest month of the year is January, when the average temperature is 1.5 °C (35 °F). The warmest month is July, with an average temperature of 17.5 °C (63 °F). August has the highest average monthly rainfall: 90 mm (4 in).

In German-speaking countries, the name of the city often causes confusion as to its origins, because it is commonly known as the German infinitive of the verb for the act of eating, and/or the German noun for food. Although scholars still dispute the interpretation of the name, there remain a few noteworthy interpretations. The oldest known form of the city's name is Astnide, which changed to Essen by way of forms such as Astnidum, Assinde, Essendia and Esnede. The name Astnide may have referred either to a region where many ash trees were found or to a region in the East (of the Frankish Empire). The Old High German word for fireplace, Esse, is also commonly mentioned due to the industrial history of the city, but is highly unlikely since the old forms of the city name originate from times before industrialization.