Here are some terms that might not be familiar to you if you're new to forums. If there are confusing words in this forum or on any of the places you might be expected to click, you can say so by clicking the Discuss this Resource button on the right side of this page.
What is a forum?
A forum is a folder.
Well, it's of course a lot more than that. I've put some comments and a link to a great Wikipedia article at the bottom.
This UBC Botanical Garden Forums is a discussion site, a place for the university community and the community at large to meet to talk about plants, gardening and natural history particularly from a regional, scientific, or UBC Botanical Garden perspective. It consists primarily of forums, threads and posts.
Starting at the top, forums on this site are organizing folders that can contain sub-forums and threads. If you're looking for postings on a particular topic, if this site is set up for discussions on what you want to read about or discuss, the postings you seek will mostly be found under forums on that topic. If you want to make a posting (= say something or ask something) on a particular topic, the place to do it is in that forum, so click on an interesting forum name to get into the forum and see what forums and threads it contains.
Note that a forum that has sub-forums may also have threads on topics of general interest at the forum level. Those will be listed under the list of sub-forums, as shown in the previous picture.
What is a thread?
Under the forums and sub-forums are the actual discussions, called threads (as in "following a thread of thought"; or you can think of postings tied together by a thread). Someone starts a posting in a forum; others reply. That set is a thread. The threads are listed under the forums, and usually when you open the forum, the thread with the most recent posting is listed at the top, followed by the thread with the next most recent posting, and so on. So the topics of current interest are at the top of the threads list in a forum. In our current system, the New Thread button is at the upper right, and it says Post New Thread.
For posting instructions, see How to post a message.
What is a moderator?
Moderators oversee specific forums. They generally have the ability to edit and delete posts, move threads, and perform other actions to keep the postings in those forums organized, on topic and in line with the goals for that forum.
What is an administrator?
This is mostly from Wikipedia: The administrators are the people who have overall control of everything that happens on the board (forum site). They oversee how the board is styled; they decide what forums to create and how to organize them, what information to require from members and whom to appoint as moderators. In addition to making sure the board continues to adhere to and support its mandate, they moderate all the boards that do not have their own moderators. A large part of the job entails keeping the board free of spam (generally obscene postings or sales messages).
The bigger Forums picture:
From historically being a city's marketplace and centre of public business, the word "forum" has become generalized to being a public meeting or presentation involving a discussion usually among experts and often including audience participation. It is now an online discussion site, originating as the modern equivalent of a traditional bulletin board. If you're interested in the whole story of what forums are and how they do it, see this excellent comprehensive Wikipedia article called Internet Forum. I found the Warnock's Dilemma link interesting, on interpreting a lack of response to a posting.