18

In science

-The atomic number of argon
-The 18-electron rule is a rule of thumb in transition metal chemistry for characterising and predicting the stability of metal complexes
-The number of years in the Saros cycle of eclipses of the sun and moon

In religion and literature:

-The Hebrew word for "life" is חי (chai), which has a numerical value of 18. Consequently, the custom has arisen in Jewish circles to give donations and monetary gifts in multiples of 18 as an expression of blessing for long life.

-In Judaism, in the Talmud; Pirkei Avot (5:25), Rabbi Yehudah ben Teime gives the age of 18 as the appropriate age to get married ("Ben shmonah esra lechupah", at eighteen years old to the Chupah (marriage canopy).

-Shemoneh Esrei (sh'MOH-nuh ES-ray)

Lit. eighteen. A prayer that is the center of any Jewish religious service. Also known as the Amidah or the Tefilah. 

-In Ancient Roman custom the number 18 can symbolise a blood relative.

-Joseph Heller's novel Catch-22 was originally named Catch-18 because of the Hebrew meaning of the number, but was amended to the published title to avoid confusion with another war novel, Mila 18.

-There are 18 chapters in the Bhagavad Gita, which is contained in the Mahabharata, which has 18 books. The Kurukshetra War which the epic depicts, is between 18 armies (11 on the Kuru side, 7 on the Pandava). The war itself also lasts for 18 days.

-A shape looking like 18 in Arabic numbers is formed by the lines on the palm of the right hand.

As lucky or unlucky number

-In Chinese tradition, the number 18 is normally 十八 (shí bā), but it can also be read as 幺八 (yāo bā), which sounds like 要发 (yào fā), meaning that one is going to prosper. Thus, building floors numbered "18" are often very expensive in China

Age 18

-In most countries, 18 is the age of majority.
-In most countries, 18 is the voting age.
-In eleven states of the United States, 18 is the age of sexual consent

In sports

-In Australian rules football:
Each team has 18 players on the field during play. The Australian Football League, the sport's top professional league, has 18 teams as of the 2012 season.

-In association football, "the 18" is a slang term for the penalty area.

The jersey number 18 has been retired by several North American sports teams in honor of past playing greats or other key figures:

-In Major League Baseball:
The Cincinnati Reds, for Ted Kluszewski.
The Cleveland Indians, for Mel Harder.
In the NBA:
The Boston Celtics, for Hall of Famer Dave Cowens. The team initially planned to retire the number for Jim Loscutoff, but he requested that the number not be retired at that time.

-In the NHL:
The Buffalo Sabres, for Danny Gare.
The Chicago Blackhawks, for Hall of Famer Denis Savard.
The Montreal Canadiens, for Hall of Famer Serge Savard.
The Los Angeles Kings, for Dave Taylor.

-In the NFL:
The Denver Broncos, for Frank Tripucka. The number was taken out of retirement, with Tripucka's blessing, for Peyton Manning, who wore the number with the Indianapolis Colts.
The Kansas City Chiefs, for Hall of Famer Emmitt Thomas.
The Colts have yet to retire any numbers during their history in Indianapolis, but have taken #18 out of circulation following Manning's departure from the team.
In addition, the University of Mississippi football program has retired #18 for Archie Manning.

-18 is also the number of a NASCAR Sprint Cup Series car currently owned by Joe Gibbs Racing. The #18 has been driven by Kyle Busch since 2008. Other notable drivers of the car include Dale Jarrett, who won the 1993 Daytona 500 in the #18; Bobby Labonte, who won the Cup championship in 2000; and J. J. Yeley.

-The number of holes on a regulation golf course

via:wikipedia.org

cbssports.com

Peyton Williams Manning: (born March 24, 1976) is an American football quarterback for the Denver Broncos of the National Football League (NFL).

 A four-time MVP, he played for the Indianapolis Colts for 14 seasons from 1998 to 2011. 

He is a son of former NFL quarterback Archie Manning and an elder brother of New York Giants quarterback Eli Manning.

Manning played college football for the University of Tennessee, leading the Volunteers to the 1997 SEC Championship in his senior season. However, No. 3 Tennessee lost to the No. 2 Nebraska Cornhuskers 42-17 in the Orange Bowl giving Nebraska and Tom Osborne their 3rd national championship in 4 years. 

He was chosen by the Indianapolis Colts with the first overall pick in the 1998 NFL Draft. Manning's playing career and statistics have ranked him among the greatest quarterbacks of all-time. From 1998 to 2010, he led the Colts to eight (seven AFC South and one AFC East) division championships, two AFC championships, and one Super Bowl championship (Super Bowl XLI). 

His five NFL MVPs are a league record, he was the most valuable player of Super Bowl XLI, has been named to thirteen Pro Bowls, has thirteen 4,000-yard passing seasons, and is the Indianapolis Colts' all-time leader in passing yards (54,828) and touchdown passes (399). In 2009, he was named the Best Player in the NFL, and Fox Sports, along with Sports Illustrated, named him the NFL Player of the Decade for the 2000s. Before the 2013 season had even finished SI had named him their Sportsman of the Year.

In May 2011, he underwent neck surgery to alleviate neck pain and arm weakness he dealt with during the previous few seasons before signing a five-year, $90 million contract extension with the Colts in July 2011. Manning had hoped to play in the 2011 season, but in September 2011 he underwent a second, and much more serious surgery: a level one cervical fusion procedure. Manning had never missed an NFL game in his career, but was forced to miss the entire 2011 season. He was released by the Colts on March 7, 2012, and after an almost two-week period where he visited with and worked out for several NFL teams, he signed with the Denver Broncos on March 20, 2012.

Manning's pre-snap routine has earned him the nickname "The Sheriff", and he is one of the most recognizable and parodied players in the NFL. Teams led by Manning more often than not use the hurry-up offense in place of the standard huddle. "Omaha, Omaha!"

via:wikipedia.org

PEYTON MANNING: 

NUMBER 18 EQUALS NUMBER 1. 

SUPERSTAR.

 GOOD LUCK PEYTON, GO BRONCOS!