The Brief: Admin and moderators (mods) are people tasked with curating or restricting content on an interactive website.
On Instagram, an admin (originally short for administrator) is a person who runs an account other than their personal account. Multiple admins can control an account and they may take submissions from other Instagram users.
Moderators or mods are often parts of Facebook groups and Reddit communities. They make and enforce rules about what should be posted, censoring posts that are off-topic or offensive. Mods are often criticized for controlling what people can and cannot post on forums.
Moderators and admin are rarely paid for their labor. They usually do it as a part of forming and maintaining functional, civil online communities.