Moderators are assigned for each forum and moderators and administrators can do the site maintenance as well as the user maintenance. Once a guest is registered with the site they become General Members of the site, and they can post new Article/question threads or reply to existing threads in the forum, they can participate in the option polls in the forums, and if the forum permissions allow they can create polls. And they can subscribe to any discussion so that they get alerts, when someone replies to that thread. And users can post threads and lock them so that others can only view them but cannot reply. Apart from discussions members are allowed to send and receive private messages with other members in the site. The more posts the user make their ranking the site goes higher.
Moderators in the site will be moderating and maintain posts in their relevant forums. If there are any forums that allow only posts after approval from moderator, then they have to read and decide whether to approve that post or reject them. And also moderators can Ban any abusive users from the website or warn them. And also they can lift off the bans or the warnings from the members after some period of good behavior in the site
Administrators who have the full control of the website, has all the features of a moderator and the general user and they can create delete forums and sections. They can give ranks to users and promote them as moderators or administrators. Administrators can send mass emails and newsletters to all the members of the website. They can physically access the script files of the forum software and modify them to tweak and update the forum software.
Even though the forum software is free open source software and has a lot of advanced and good features to run a website, the forum only interface is not familiar to all the users who use internet, and it is very hard for beginners to find what they want exactly. And the less attractive interface of the website drives away the new users who visit the website.
And the sites forum software requires a high maintenance, because of very frequent patch releases and mainly because of SPAM. And customization of the software requires extensive knowledge on PHP scripting, and even a small mistake while the upgrade process might result in loss of entire site, and most of all once the software is customized the official providers of the software will not provide support in any cases which again leads to high risk.