A Special Interest Group, aka SIG, is a group inside a large organization that works on a specific play style or region. Rather than rely on the CEO to make decisions, it has a unique set of leaders only inside that SIG. The SIG is supported by the larger organization through money, encouraging players to join, and propaganda to show successes. Note, some groups call these things somewhat different.
These SIGs can range from PVP forward deployments, Spy networks, farming PVE instances, or even mining gas. Some require strict anti-spy technology, while others can be much more open.
What makes a successful SIG depends heavily on both the leadership and the membership, with both working in concert. If leadership stops leading fleets, the SIG will generally die. If the membership loses faith in their leadership, the efforts can die off. If CCP changes conditions to make things less valuable, this can also spell the end to a SIG. The best thing to do with a failing SIG is close it up and open a different one under new management.
Arguably the most important point of a sig is having clear limits on what they do and don't do.
Do they operate in a specific region?
Who do they accept?
What content do they do?
Do you call in the main alliance or coalition forces to help?
Do they have the resources to do the job?
These ideas are important establish, up front, and make it clear why the SIG is different than the original group.
Having a snappy name is REALLY important. It gives a small group a feeling of independence and comradery. Showing success inside that sig depends heavily on it being tied to the name. I will expose a couple groups I have been a part of to show the inner workings a bit.
Goonswarm have some of the longest running sigs still in operation. Most of their modern ones are named after bee related things. This is because they have used Fat Bee as their logo. These are publicly available on their own wiki as well: https://wiki.goonswarm.org/w/Sigs_and_squads Some examples of longer existing ones which don't follow the theme:
GSOL = Goonswarm Offensive Logistics - Deals with infrastructure inside goon space. This acronym makes it easy to contact those who deal with space structures thare complicated and require roles to deal with. Used to be more accepting of interested players, but now very restrictive in who they recruit to help them.
Black Ops = Does small scale camps using cloaky ships, surviving long periods of time without dying. Used to be a huge name in the community thanks to a very active leader, but has since fallen into disrepair due to being ignored. High skill point players with great small gang pvp skills was the requirement.
CD = Corps Diplomatique - The Goonswarm diplomatic arm, talking with other organizations. CD was originally led by my friend https://www.eveonline.com/news/view/csm-tribute-to-vile-rat Was easy to join when they were doing recruiting, just being good at talking.
EG = European Goonion - Was maybe the strongest SIG in the game due to it's ability to find spies and backed by a very strong FC, Mister Vee. Was invite only, hard to enter, and was very effective at fighting larger groups.
All of these groups go through arcs of ups and downs of activity. Some cannot stop, like GSOL, because as the Mittani once said: "Well, I need someone to fuel my towers." PS. that was Kismeteer for 6 years.
Goonswarm has now splilt SIGs and Squads, depending on how they are being organized. This gives more independence.
Arriving later in the game, Pandemic Horde also has group names similar to their theme, the bean. The Pandemic Horde logo is based on a bacteria looking character sitting on a Scooty Puff Junior, which looks somewhat like a bean. Because the importance of the aligning a function with a corp specific theme was not recognized till later, most of these are much more 'on theme' than Goons. https://www.pandemic-horde.org/forum/index.php?threads/bean-interest-group-megathread.3444/ has their thread, but is closed behind joining horde.
NBI = New Bean Initiative is one of the oldest organizations in PH. Its designed to help new players get their hang of the game. Because of PH's founding, getting new players to join was important, so establishing a bitter vet group to help the new players was important. This name uses a very easy acronym that makes it easy identify. NBI also refers to the 16 free ships PH hands out, so NBI has two different usages inside Horde. This group has a strict process of getting new members.
Fresh Beans = This group contacts new players in an organized fashion to confirm that players are getting the hang of the game. They also follow up later to confirm people are getting the most out of the organization. Because these people are only talking to new players, this is actually very easy to join.
Capital Group = Names for what it is, those who drop capitals. These have strict skill requirements that takes years to train. But once you are in, if we have a massive drop, you can drop with them. These can lead to other corporations inside Horde, but does not require ESI-status.
The are a massive number of SIGs out there, but most are closed to outsiders. Some have made their name beyond their group, and I would love to give a feel for any others you know of.
Brave Dojo - The training arm of Brave Newbies. These groups hand out the free ships that Brave has for new players.
It's very important to make it clear in a SIG of your purpose, but more importantly in eve, it's more important to know what requires comms discipline and what is available to know for all.
If you are inside a SIG, you often will get your own discord channel or possibly your own discord. It's very important NOT to share outside your SIG if it's closed communications.
Some examples are:
Holey Beans is a group inside horde. You don't share where there is gas to be mined, but you do invite people to join, since it's easy to join.
PANKRAB status is supposed to be a secret, it's either up, or it's down, and you don't share that information. But a lot of people break this rule. Eventually, those people might lose their statatus as a member of the organization.
Any of the whaling sigs, if you share when you are active, you will be purged as a spy. And maybe blacklisted from the coalition.
Running a sig sometimes has very similar rules to running a full corporation. See Corp Management for more ideas on success.
Players are giving you valuable time to support your organization, make sure to reward those people. This can be in the form of isk payouts or plex or just free ships. Having a successful Ship Replacement Program aka SRP is the main requirement.
Note, sometimes the effort is enough of a reward, or the results of your labor. Joining a faction warfare SIG, for instance, gets you payouts directly.