I'm just getting my feet wet with investing in individual stocks. I purchased a book by William J. O'Neil (The successful investor), it's good.

My question is about bar charts. If I'm looking at the DJIA in bar chart format for one day of trading I see short vertical lines with two teeny-weeny horizontal bars one on each side. I think that one one horizontal bar on the left is the opening price and the right is the closing price.

That's kind of odd though if I'm looking at trading for one day. Anybody see what I mean?