short for Weblog
First Known Use: 1999
: a meeting at which a subject can be discussed
: a place or opportunity for discussing a subject
So, if you write about how you set up your planted tank, show some photos, and then update those over time, you are blogging. You can also have discussions about how other people address the same problems, but mainly you are telling an ongoing story about something you did.
If you ask a question, without actually telling any story about something you did, and expect an answer, you are actually using a forum. Forums can also be about idea exchanges, where many people give diverse opinions about how they would do something about what they have done.
Is this a petty distinction.... probably. Does anyone else think like this?.... Oh crap! I think I just changed this into a forum...... I am confusing myself.