So far, there's only one item there – runlevel definition. Obviously, it's a work in progress, so I'll be updating definitions constantly and expanding the section as I post more.
The plan is to have a Unix Glossary section at the bottom of each post on Unix Tutorial, so that it gives you another chance to expand your understanding of Unix basics.
If you have any terms from Unix world which you'd like me to cover first, please head over to the Unix Glossary page and leave a comment there with your suggestions.
Let me know what you think about this, do you think it will help? If there's any other side of this blog you'd like changed or improved – just let me know. I'm using this blog as my own reference all the time, so I always appreciate your feedback as it makes life easier and Unix Tutorial better for everyone.