The Vongola Famiglia has long since been the most powerful Mafia family in all of Italy since its creation 400 years prior to the start of the series.
They are considered to have a violent and bloody history, and have had several other Mafia families and organizations serving them, including a few members from the infamous Arcobaleno.

Giotto a.k.a. Vongola I (Primo) is the founder of the Vongola Family.
He was known to have had an unorthodox family; that is, he accepted anyone he liked, including kings, military men, rival Mafia members, and even religious people.
The organization has also been on the receiving end of secret black ops military technology, which has bolstered their strength over the years.

Those who inherit the Vongola bloodline have certain unique traits; some traits are consistent, with every Vongola in each generation possessing it like heightened intuition, while sometimes it would skip either one or possibly even several generations.
They also possess the Vongola Rings, seven invaluable rings which have been around since the founding of the Mafia underworld and are usually in possession of the main members known as the Vongola Guardians.
They are also rich in various traditions, most notably the Vongola Tournament, a traditional battle in which two groups vie for the seven guardian positions.




The Vongola Rings are priceless, and powerful Vongola treasures, and part of the Tri-ni-sette.
The types of Flames emitted by rings are named after these rings.

Sky for orange ,
Storm for red
Rain for blue
Cloud for purple
Lightning for green
Sun for yellow
Mist for indigo

Vongola Rings are used to signify the leader of every generation of the Vongola and the six people most suited to be his or her guardians.
The Boss is always a natural born Sky type. It is even said that the ways that these guardians are chosen sometimes relate to their relationships with one another, such as the Cloud sometimes being a catalyst for the Storm.




The Arcobaleno (which means "rainbow" in Italian) is the group of the seven strongest infants, who each possesses a pacifier colored as one of the colors of the rainbow, with each color corresponding with their Dying Will Flame.
Their pacifiers will glow when a member nears another Arcobaleno.

They were all transformed from adults into their current forms, having sacrificed themselves in order to protect the "7³", or "ultimate power".
Each of them gained their own "curse" and specific abilities, and are able to emit the Dying Will Flame throughout their entire body.

Colonnello is revealed to have not been part of the original seven, and had instead taken Lal Mirch's place during the day they were transformed.
An image of the entire group reveals the two remaining members to be Luche, the holder of the orange pacifier, and Fon, the holder of the red pacifier.
Luche is also Uni's mother and the former leader of the Giglio Nero Family, while Fon is I-Pin's master.




The Kokuyo Gang is a group led by Mukuro Rokudo, who formed the group after escaping from a special, high security jail in Italy which housed heinous criminals who have even committed crimes against the Mafia.
Along with the two comrades he escaped with, Ken Joshima and Chikusa Kakimoto, he recruited other Mafia criminals who were able to break out from the same jail some time later.

After their defeat at the hands of Tsuna and his friends, they were all once again imprisoned, though Chikusa and Ken are later able to escape, while Mukuro strikes a deal with the Vongola for their safety.
Prior to making their appearance, Amano wanted to use only 3 members for the gang, with Mukuro being the only one who had the same appearance as in his introduction.




The Varia is the Vongola Family's elite, independent assassination team.
They are composed of genius assassins who work in the deepest recesses of the Mafia.
Each member takes on missions that are said to be impossible to accomplish by humans, however, they do not accept a mission unless they believe there is a 90% chance of success.
Those that see them work often say that their high level assassination skills are demonic. Despite lacking loyalty and respect for other members, they are extremely loyal to their leader, Xanxus.
The Varia also appear to have more than fifty subordinates ranged under the command of the main members. The Varia is apparently reclusive, only showing themselves after Iemitsu Sawada disappeared.

During the alternate future arc, a 32 member Varia squad led by Xanxus attack a Millefiore base in Italy in accordance with the Vongola's plan to eliminate the Millefiore.
Despite their fierce loyalty to the Vongola Family, the Varia only consider themselves as the Vongola IX's assassination team, still not acknowledging Tsuna to be the rightful Vongola X.




The Millefiore Family is the Mafia family that is engaged in battle against the Vongola Family in the future.
The Millefiore is a result of the merging of two separate Mafia families: the up-and-coming Gesso Family led by Byakuran, and the family with as much history as the Vongola, the Giglio Nero led by Uni.

They are organized into two groups to distinguish their old families, which are then further separated into 18 different squads, each named for a plant or flower.
Those originally from the Giglio Nero are the Black Spell and have the tendency to engage in direct combat, while those from the Gesso are the White Spell and specialize in cunning battle tactics.
There appears to be animosity between members of the White Spell and the Black Spell, resulting in a lack of communication and sabotage by individual squads.
Their organization also possesses the Mare Rings, a set of seven rings on par with the Vongola Rings originally belonging solely to the Giglio Nero.
The holders of which, save the holder of the Sky, are known as the six Funeral Wreaths.

Source: Wikipedia