Lawns are a standard or essential feature of ornamental private and public gardens and landscapes in much of the world today. Lawns are created for aesthetic use in gardens, and for recreational use, including sports. They are typically planted near homes, often as part of gardens, and are also used in other ornamental landscapes and gardens.
Lawns are also a common feature of public parks and other spaces. They form the playing surface for many outdoor sports, cutting erosion and dust as well as providing a cushion for players in high impact sports such as football, cricket, baseball, golf, tennis and bowling. In sports venues, the term lawn is usually replaced by turf or green.
Several different species of grass are used, depending partly on the intended use of the lawn, with vigorous, coarse grasses used where active sports are played, and much finer, softer grasses on ornamental lawns, and partly on climate, with different grasses adapted to oceanic climates with cool summmers, and tropical and continental climates with hot summers.
Important cool summer grasses include species of Agrostis (bent), Festuca (fescue), Lolium (ryegrass; the most important sports grass), and Poa (meadow-grass or bluegrass). Important hot summer grasses include species of Cynodon (bermuda grass) and Zoysia (zoysia grass).
Lawns cover a significant area in the United States. In a recent NASA-sponsored study, researcher Christina Milesi estimated the area covered by lawns to be about 128,000 square kilometers (nearly 32 million acres) making it the largest irrigated crop in the United States, about three times that of irrigated corn. 
Lawncare is big business in America. Estimates of the amount spent on professional lawn care services vary, but a Harris Survey put the total at $28.9 billion in 2002, which calculates to roughly $1,200 per household, spread over the 24.7 million households who use such services.
Virginia Scott Jenkins, in her book The Lawn: A History of an American Obsession (1994), traces the desire to kill weeds historically. She notes that the current rage for a chemically-dependent lawn emerged after World War II, and argues that “American front lawns are a symbol of man’s control of, or superiority over, his environment.”
Approximately 50-70 percent of U.S. residential water is used for landscaping, most of it to water lawns.
Along with trees, lawns are a vital player in the fight against urban heat islanding. They provide oxygen conversion, filtering of air particulates, erosion control, air and surface cooling to offset miles of new asphalt, cement, and rooftops. In comparison to bare dirt, a lawn may be 20 degrees cooler on a hot day, and up to 40 degrees cooler than cement surfaces.
Maintenance, construction and management of lawns of various kinds are the focus of much of the modern horticulture industry.
Maintaining a rough lawn requires only occasional cutting with a suitable machine, or grazing by animals.
Higher quality lawns however require a number of operations. These may include:
- Mowing, to cut the grass regularly to an even height
- Scarifying and raking, to remove dead grass and prevent tufting
- Rolling, to encourage tillering (branching of grass plants), and to level the ground
- Top dressing the lawn with sand, soil or other material
- Spiking or aeration, to relieve compaction of the soil
- Watering, to prevent from going dormant and turning brown
- Pesticide application to manage weeds and pests