The option bar is directly related to the object you have selected. It gives you…wait for it…options for the object.
For example, if you have a text box selected, you would expect to be able to change the font, text size, text orientation, color, etc:
If you have a shape selected, you can change the fill color (inside), the stroke color (outline), or perhaps the opacity:
If you have an image selected, you will be given options for it’s placement on the page:
This is an easy one to understand. Just remember that it changes with the object you have selected and it will give you specific options based on what the object is.
Again, this is a VERY QUICK outline for the tools. These are the things I wish I knew when I was getting started.
If you want a more comprehensive rundown, check out my free Graphic Design in Illustrator introduction video tutorials.
Did I leave anything out? Is there anything that is confusing you? Let me know in the comments below!