What makes college football so exciting and full of energy?
In a word—fans.
It's all about the fans when it comes to college football.
Stadiums fill up to 100,000-plus with crazed fans locked shoulder-to-shoulder to go wild for their team every Saturday.
There are certain fan bases, though, that gain a reputation as a nasty group allowing no mercy for visiting opponents.
Sometimes it's all about one small chant; other times it's simply everything about these fans that strikes fear in their opponents' hearts.
Here is a look at the 15 most ravenous and boisterous fan bases in college football.
Boise State has been in the mainstream of college football for mostly only this decade, but better late than never.
Bronco fans have quickly gained a rep for being loud and annoying among opposing players, particularly Oregon running back LeGarrette Blount, who almost charged into the stands after jeers from BSU fans.
Bronco Stadium only holds a little over 30,000 people, but those fans are quite loud, and the blue and orange travel very well.
We haven't seen the last of Boise State, and this team is quickly gaining a large and rabid fan base along the way.
Hokie Nation is charged with having probably the greatest intro in college football, where "Enter Sandman" by Metallica is blasted through the speakers and the stadium rocks as VT takes the field.
These fans are some of the most passionate in the country, especially when they welcomed their team back to the field for the first time since the horrific shootings in April of 2007.
Hokie fans get loud like the best in the country, and they have tremendous pride, with the "Old Hokie Yell."
The successes of the VT football team in the past decade have had a lot to do with their rep, but the passion of these fans can never be ignored.
Texas football is steeped in tradition and is essentially a religious experience.
The same can be said for the fans of the Longhorns, who pack DKR Memorial Stadium by the thousands.
Everything from "Texas Fight" to the "Hook 'em 'Horns" are iconic traditions of the Texas fan base, one of the largest in the country.
And in the last few seasons, these fans have had a lot to cheer about, from Vince Young's title run to that magical 2009 and a national title game appearance.
As expected, the passion of Texas football fans is something to behold.
It's no secret that the stadium with the largest capacity in America has some of the loudest fans to go along with it.
And like fans of Big Ten schools, the fan base of Michigan is steeped in tradition and rituals.
From the honoring of legendary coach Fielding Yost to the mass singing of "Hail to the Victors," the Wolverine faithful rock the Big House every chance they get.
Unfortunately, these fans haven't had much to cheer for in recent years.
The fans have stayed loyal nonetheless, but they are desperately hungry for another winner worthy of the elite company in college sports.
Despite that, there is no question that the Michigan fans are as good as any in the country.
Georgia football, like most SEC schools, carries a fan base as hungry and nasty as the games in which the Bulldogs play.
All it takes is the mass barking at Sanford Stadium to send a chill down an opponent's spine, not to mention the red and black pom-poms fans bring to every game.
Traditions such as "Hunker Down Hairy Dawg" and the Chapel Bell ringing are staples of what makes Bulldog fans special.
And with all the rivalries UGA shares, it doesn't take much for fans to get riled up and crazy in those big game.
Way up in the north of Madison lies one of the best-kept secrets in college football—and one heck of a nasty fan base.
Badger fans are just as nasty and loud as the badger itself, and they pack Camp Randall Stadium in droves, making it quite a tough place to play.
But it gets much tougher after the third quarter, when House of Pain's "Jump Around" blares through the stadium and the fans literally jump up and down, shaking the place to its core.
That is just one of their many traditions up in Madison, but Wisconsin fans are best known as very nasty fans that endlessly heckle opponents.
They have a lot of pride in their Badgers, and they're never afraid to show it.
Gator Nation has featured some of the most crazy fans over the years, and they have had a lot to cheer about when it comes to their beloved Gators.
These fans clad in blue and orange pack the stacked Ben Hill Griffin Stadium, standing right on top of the field.
And when these fans crank up the "Gator Chomp," it means you as an opponent are in for a long 60 minutes of football.
In addition, "We Are the Boys" has become a mainstay of UF fans wherever they go to watch the Gators play.
And with the success the program has had, the fans have a lot to be proud of and a lot of reasons to cheer.
Auburn football has quite a name for itself, with eight national titles of some sort (as recognized by others) to show for a great history.
And when its fans pack Jordan-Hare Stadium, it can get quite nasty at Running Back U.
Most notably is the infamous "War Eagle" chant, which reverberates through the stadium when the eagle is released and flies around the stadium.
And the Tiger fans rock the "Zombie Nation" chant in a way that few schools in the country can hope to match.
"The Jungle" is always rocking because it's the AU fans that keep it going every Saturday.
Being the program of the 1990s, Florida State quickly burst onto the national scene with its strong football performance.
But one of the more memorable sights in Tallahassee is Seminole Nation, the crazed fan base of FSU football.
And they boast what is possibly the most unique and intimidating chant in the nation: the "Tomahawk Chop" and chant.
It is utterly hypnotic and intimidating at the same time, especially when the 'Noles are on their game.
And Doak Campbell Stadium erupts when Chief Osceola plants the flaming spear into the turf.
All of this combines to make the Seminoles fans some of the best in America, even though the program has fallen on hard times lately.
Notre Dame fans take an incredible pride in their program, and they are as demanding of success as they come.
No fan in South Bend would ever tolerate losing, and they put their hearts into cheering for the men that wear the gold helmets.
And when the "1812 Overture" is played after the third quarter, the stadium begins to erupt as they cheer the Irish on for the final stretch.
The pride of the Irish program carries on through to the fans, who never waver and would give their support until the end.
Tiger Stadium is forever known as the place where crowd noise actually registered on a seismic meter.
The fans that pack this stadium have earned their billing as some of the rowdiest fans in the country.
Everything from the "Geaux Tigers" chant to the massive noise levels they can reach, especially after "The Catch" in 2007, gives these fans quite a reputation to be reckoned with.
These fans are always quick to remind visitors where they are, with their famed "Tiger Bait" chant.
When you go to LSU or they head up to your town, brace yourself for how crazy and proud these fans will be.
As Oregon football has grown, so too has the rep of the Ducks' fan base, one of the loudest in America.
It's tough to get a seat in Autzen Stadium, but the lucky ones that do leave with a sore throat—and, most of the time, a smile.
The "O" chant gets the crowd going, and the volume is always constant from these crazed fans.
And they do travel well, as you can see many UO fans wherever they go for road games.
Oregon football is on the rise, and the Ducks' fans will only continue to grow in number and volume.
There is possibly no bigger network of alumni and fans than at Ohio State, where fans specify that it is "THE Ohio State University."
The reputation for their fans is being loud, crazy, and deathly loyal.
And lately, some have accused the fans of being too greedy, where 10 wins is now an expectation instead of a success.
But, really, it's about pride and history.
Everything from "Stadium O-H-I-O" to "Hell's Bells" on every defensive third down makes Ohio Stadium, aka "The Horseshoe," erupt tremendously.
And lately, the new "Seven-Nation Army" chant has become the calling card for OSU fans, as witnessed in their 2009 game against USC.
Ohio State has some of the most prideful and rabid fans in the country, and they are proud of it as well.
If you look for the definition of pride personified, look no further than the Alabama faithful.
These fans cram into Bryant-Denny Stadium and rock the building in a way that gives almost nobody a chance to beat the hometown Tide.
Everything from the red-and-white pom-poms to the "Roll Tide" chant are iconic of the loyal fans.
And everyone knows that the Tide has won when they hear "Rammer Jammer Yellow Hammer" everywhere they go.
Lately, Alabama fans have witnessed a lot of winning, with only two losses in two seasons and the latest in a long line of national championships.
When it comes to tradition and pride, no one wears it better than the Crimson Tide.
Clearly, no fans, especially from a student standpoint, get more into a game than those from Penn State.
The Nittany Lions' faithful have an endless array of cheers and gimmicks, especially the infamous whiteout and the student "S" in the stands.
These are unquestionably the craziest students in college football, and they literally rock Happy Valley, which becomes the third largest city in Pennsylvania on game day.
Every year they get into big games with the whiteout, which has become a nationwide tradition after the Lions led the charge as the first school in the modern era to encourage all attendees to wear white.
Many sports analysts from year to year consider PSU to have the best fans in the country and the rowdiest come game day.
And the success of the program in recent history certainly has a lot to do with it.
But no fans are as boisterous game-to-game like those at Penn State.