A lot of times when we read the Bible, there are passages that are confusing or we want to understand better. The first impulse is to send Bert an email and ask him about the text. While Bert is often the Bible answer man, we sometimes have these questions when it is not convenient to ask him. Hence, we turn to a Bible commentary. While there is a huge range of them and many free ones online, one that I have turned to from time to time (but forgot about until recently) is by Dr. Thomas Constable from Dallas Theological Seminary in the US.
He is a Biblical studies professor in the US and has written notes on every book of the Bible, available for download as PDFs. In each of the PDF files, it gives you the basic historical background, an outline of the flow of the book, and his exposition (or commentary) on every verse within the text. If you want to read more, he has a helpful list of additional books you can refer to at the end of the file. But, for most people, this is actually quite substantial.
Now, if you are going to be a Bible scholar or want to know the nit-gritty debates on certain verses, you are probably not going to find it here. For that, you need more “critical” or “technical” commentaries. However, for the average person and for the average study, this is an excellent resource.