If a creature in combat has banding, its controller assigns damage for creatures blocking or blocked by it.

If a creature with banding attacks, it can team up with any number of other attacking creatures with banding (and up to one nonbanding creature) and attack as a unit called a "band." The band can be blocked by any creature that could block a single creature in the band. Blocking any creature in a band blocks the entire band. If a creature with banding is blocked, the attacking player chooses how the blockers' damage is assigned.

A maximum of one nonbanding creature can join an attacking band no matter how many creatures with banding are in it.

Creatures in the same band must all attack the same player or planeswalker.

It does prevent damage from animated Deserts in combat.

Camel : règles, fonctionnement et interactions (MTG)

Camel is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Banding (Any creatures with banding, and up to one without, can attack in a band. Bands are blocked as a group. If any creatures with banding you control are blocking or being blocked by a creature, you divide that creature's combat damage, not its controller, among any of the creatures it's being blocked by or is blocking.) As long as this creature is attacking, prevent all damage Deserts would deal to this creature and to creatures banded with this creature.

How it works : Camel

Original English text — Wizards of the Coast / Scryfall

#1October 1, 2009· Wizards of the Coast
If a creature in combat has banding, its controller assigns damage for creatures blocking or blocked by it.
No other card is named in this ruling.
#2October 1, 2008· Wizards of the Coast
If a creature with banding attacks, it can team up with any number of other attacking creatures with banding (and up to one nonbanding creature) and attack as a unit called a "band." The band can be blocked by any creature that could block a single creature in the band. Blocking any creature in a band blocks the entire band. If a creature with banding is blocked, the attacking player chooses how the blockers' damage is assigned.
No other card is named in this ruling.
#3October 1, 2008· Wizards of the Coast
A maximum of one nonbanding creature can join an attacking band no matter how many creatures with banding are in it.
No other card is named in this ruling.
#4October 1, 2008· Wizards of the Coast
Creatures in the same band must all attack the same player or planeswalker.
No other card is named in this ruling.
#5October 4, 2004· Wizards of the Coast
It does prevent damage from animated Deserts in combat.
No other card is named in this ruling.

Interactions with other cards

These cards' text mentions Camel.

Jandor, Fortuned Traveler

Each Beast, Camel, Horse, Elephant, and Wolf creature you control is a Mount in addition to its other types and has saddle 2. (Tap any number of other creatures you control with total power 2 or more: That Mount becomes saddled until end of turn. Saddle only as a sorcery.) Whenever a saddled creature you control attacks, it gets +2/+2 until end of turn. Draw a card. Create a Food token.