You have probably already noticed that almost all of the buildings (except residential buildings) buy some resources and produce others. For example, a Manufacturing Factory buys electricity, goods of Heavy Industry and Office Services and manufactures products of manufacturing Industry.
These goods can be easily accessed - when there is a balanced market or a surplus. They can also be difficult to get - when there is a shortage of them and/or your objects do not keep up with production. The city is a part of a giant network of commodity dependencies.
Some of these "goods" are municipal services and it's the city which provides them - by building a power station you will generate electricity and by setting a landfill you will ensure waste collection; by building an oil well you will extract fuel.
A big part is produced by other objects in the city - factories of subsequent levels provide adequate goods that are consumed by the city for their own purposes or for export. By constructing office buildings you will provide office services to companies that work much worse without them.
Some goods, however, such as fuel, water, food and tourism are determined by the map. If the map does not contain land with oil, you will have to import fuel from other cities. If you have a large amount of fertile soil on your map, it is good to export food.
Another problem can be providing adequate services only indirectly dependent on your management. Most of the factories need transport services to prosper well. They handle it on their own but their quality depends on how easy it is to get out of town. The more traffic problems there is in city, the more difficulties there are with transport services. Sometimes you have to run to extremes - demolish some of the buildings to build a new wider road. Its costs will be recompensed by taxes which will increase - they are calculated according to profits of companies.