Group

A group is the third smallest known unit in the Covenant Army. The term "group" was allegedly coined by a character referred to as "Taylor". A group is the rough equivalent to a UNSC or Spartan-IV platoon. A group is superior to a lance.

Background
Groups usually contain a core of sixteen to nineteen members, which is typically three lances. Groups also sometimes contain support, which can be a team of Unggoy Heavies, Jackal Snipers, Skirmisher Murmillones or Skirmisher Commandos. Groups may also contain vehicle support from smaller vehicles like Ghosts or Revenants, while Wraiths, Banshees and Locusts are attached to the operational command. Groups may also include engineers sometimes. Often times, there is one group per Spirit dropship or one or two Phantom dropships.

Special Operations
Special operations groups usually contain three lances made up of unggoy (commanded by a Special Operations Sangheili or an Unggoy Ultra) along with some Special Operations Unggoy and Unggoy Ultras using heavy weapons as support or riding in ghosts. Special operations groups are typically led by Special Operations Officers.

Unggoy/Kig-Yar
Most groups are mixes of Unggoy and Jackals, although they may contain only Unggoy or only Jackals. Groups are led by a Sangheili Major and will usually contain three lances as well as support teams of two to four Unggoy Heavies or two Jackal Snipers. They may also contain one or two ghosts or revenants, with Ghosts typically being piloted by Unggoy Minors, Majors, Heavies and Ultras (or even a Sangheili Minor) and Revenants typically being piloted and rode by Sangheili Minors and Majors. Groups can be made up of mixes between Unggoy and Jackals, but scouting groups tend to have more Jackals while infantry groups tend to have more Unggoy. In less common cases, a Sangheili Major-led group may contain Skirmishers, in which case they would be organised like Jackals and fall under the command of a Sangheili Major, not a Skirmisher Champion. Support for groups may also include hunters, teams of Sangheili Rangers, Stealth Soldiers or one or two Shade turrets.

Skirmisher
Skirmisher groups are usually all skirmishers and contain no vehicles or Sangheili. A typical Skirmisher group is commanded by a Skirmisher Champion and consists of three Skirmisher lances, each containing four Skirmisher Minors and two Skimisher Majors. Support for Skirmisher groups are usually teams of two to four Skirmisher Murmillones and Skirmisher Commandos. Skirmisher groups are shock groups and are made up exclusively of Skirmishers.

Trivia

 * Group is not a canon Halo unit, the term was invented by the creators of the series. In the series, according to Austin Rossi, his character on the show, so far known as Taylor, coined the term.