Company members each have a Rank. Depending on their Rank, members have access to perform various actions on behalf of the Company.
Every Company has a Governor who has all possible permissions. The Governor is the leader of the Company, and holds the power to set the status of every other member. For the Governor to leave the Company, they must promote a different member to be the new Governor. The only exception is if the Governor is the only member of the Company, in which case they cannot leave it without joining a new one.
The Ranks tab of the <a action="GoToPage" data="Mechanics_UI">Company screen</a> allows you to explore all the available ranks and their permissions. Additionally, most Company <a action="GoToPage" data="Companies_Building">Structures</a> can have a rank requirement set. This allows Companies to have even more fine grain control over who can use each Structure.
Higher ranks offer a member more potential since they can access more aspects of the Company, but they also offer risk to the Company because the member could then sabotage things. Beware of spies and double agents.