An Alliance is a group of Corporations. Multiple corporations together are able to do things which a sole corporation may not be able to do, such as hold sovereignty.
Forming an Alliance
Forming an alliance costs one billion ISK, and there is an Alliance Maintenance Bill which must be paid monthly, which is two million ISK for each corporation in the alliance. So an alliance with 20 members would cost 40 million ISK per month in maintenance fees. The Alliance Maintenance Bill is taken from the corporation wallet of the executor coproration, and can be set up to be paid automatically each month.
To form an Alliance, you must be the CEO of a corporation which is not currently in an Alliance. You must also have the following skill:
Joining an Alliance
Too apply to join an alliance, go to the Corporation window, then the Alliances and the Rankings tab. Find the alliance you wish to join, right click and select Apply to Join. You will have an option to add some information in a free text box. You can only apply to one alliance at once, so if you have a pending application it will be withdrawn if you apply to a different alliance. Once you have submitted your application you can't view it under the My Applications tab. But if you try to apply again it will tell you that you already have sent an application to this alliance.
When your application has been submitted, the Executor corporation will be able to view it under the Alliances and the Applications tab and Alliance tab. They do not receive a notification to tell them there has been a new application to the alliance. To accept or reject an application, they can right click on the application in the Applications tab and Alliance tab, click View and select to either Accept or Reject the application.
Each alliance has an Executor Corporation, who deal with the administration of the alliance. To be an Executor, the corporation must have the support of the CEOs of at least 50% of the member corporations. To support an Executor corporation, the CEO must go to the Corporation window, then the Alliances and the Members tab, select a member corporation from the list and click Declare Support. The Executor corporation will be displayed in the Alliance Attributes.
The Executor corporation is responsible for paying the Alliance Maintenance Bill, and if this is ever unpaid, the alliance will be closed at the following downtime. It is therefore extremely important to ensure this bill is paid. It can be set up to be paid automatically under the bill pay settings.
Alliance standings can only be set by the Executor corporation. They can be seen under Corporation window, then the Alliances and the Alliances Contacts tab. See Corporation diplomacy for information on how to set standings, as the mechanics are the same if you are the Exector corporation.