Every weekend, millions of people around the world make the pilgrimage to their favorite sports team and watch their sporting heroes and heroines in the flesh.
As sports science, analysis and detailed statistics transform the way teams prepare for games, arenas are also changing, with many looking to "go green."
Here, CNBC takes a look at some of the stadiums and teams embracing clean energy and the environment.
Home to the Boston Red Sox, Fenway Park is one of baseball's most iconic venues.
In 2008, the Red Sox installed solar thermal panels at the ballpark.
The panels are used to help heat water used on site, and save both energy and money. What's more, the panels help the Red Sox avoid 18 tons of CO2 emissions every year.
The home of English football – or soccer, as it's known in the U.S. – Wembley Stadium is powered by 100 percent renewable energy and is a zero waste-to-landfill venue.
Between 2007 and 2014, electricity use and related carbon emissions were cut by 30 percent.
In 2016 it was announced that Irish energy provider SSE Airtricity would supply the Aviva Stadium's gas and electricity using "clean, green energy."
The stadium is also home to waterless urinals which help to save "a minimum" of 20,000 liters of water on event days. Rainwater, meanwhile, is harvested and used in the stadium's pitch irrigation system.
A solar power system was installed at the home of the San Francisco Giants in 2007.
It has gone on to provide enough energy to power more than 5,200 homes.
The New Lawn is home to Forest Green Rovers, who play in English soccer's League Two.
Solar photovoltaic panels have been installed on the stadium's roof, while in 2015 the club announced it would sell only vegan food from its food stalls.
Appropriately, the club's chairman is Dale Vince, the founder of renewable energy company Ecotricity.
Dartford Football Club may be playing in the lower rungs of English soccer, but their stadium boasts a host of green features.
These include solar panels, a "living roof" which offers natural air filtration, and a system for the recycling of water.
Soccer club Arsenal's Emirates Stadium has become a beacon for sustainability.
It uses a water supply which is recycled to help reduce waste, while food waste is sent to an anaerobic digestion plant where, the club says, "it is turned into more energy that will in turn supply the club."
In August, the club announced its transition to being supplied by 100 percent renewable energy via its official energy partner, Octopus Energy.
Home to four sporting franchises – the L.A. Sparks, L.A. Lakers, L.A. Clippers and L.A. Kings – the Staples Center boasts 1,727 solar panels on its roof. This system is connected to another one located on top of the adjacent Microsoft Theater.
According to the website of the Staples Center, the two systems will help to eliminate more than 10,000 tons of CO2, over 27 tons of sulphur dioxide and more than 33 tons of nitrous oxide.
The Philadelphia Eagles' home turf has 11,108 solar panels and 14 wind turbines, while 99 percent of waste produced in the stadium is diverted from landfill.
According to the Eagles, all of its operations are powered by the sun and wind, while they recycle over 850 tons of material annually.