In the Online Bible there are quite a few commentaries which can be consulted. 

What makes this functionality useful is that they can be read in combination with a translation i.e. seen simultaneously. They can also be synchronised, so that moving through the Bible text scrolls the commentary automatically. 

This is possible in all versions of the Online Bible.

1. Windows version.

There are several ways to open a commentary. One is to use the right mouse button in the screen with an open Bible. A pop-up screen appears. Select the option "Open Note" and you get a list of available commentaries for that Bible book. Make a choice and the commentary appears in a separate screen. If you cannot see it, check in the menu under "Window" how your screen is set up. If it is "Tile default" change that to e.g. "Tile vertical and horizontal". 

If you have set up a favourite commentary, you can also double-click on a verse number and it will open. 

You decide which commentaries are shown in Favourites (if not visible on the left of the screen, press F9). In the vertical tab, select commentaries and check the ones you want. See the following articles for details: Setting up the favourites

When you now go through the text of the Bible, the commentary should also move to keep aligned. Note some commentaries do not contain comments about all verses. If the commentary is not synchronised, this can be changed by going to menu item "Window" and ensuring "Synchronse scrolling" is selected. 

You can also open a commentary without going through a Bibe translation. In the menu choose File >> Open >> Note/Commentary (or press F2). In the pop-up screen you can choose commentary, Bible book, chapter and verse. 

2. In macOS

In the screen with an open Bible you can choose a commentary from the list on the left. It will open in a screen under the Bible. 

Click on the two squares (so the top one turns blue) to synchronise Bible text and commentary :

If you click on the reference in the title of a commentary, you can choose the relevant Bible verse. If there is an entry for that verse it will appear. 

3. In the Android and iOS app

To see commentaries in the Android and iOS (iPhone/iPad) apps you have to be aware that there is asecond screen. The example below if deom an Android smartphone, but iOS and tablets work the same way. 

At the bottom of the screen there is a green bar with three black lines in the middle. Click on this, or slide it up to show the second screen. 

In the darker green section you can choose a commentary on the left. Various types of material can be opened in this second screen: commentaries, dictionaries, lexicons and other books. In the drop-down list, make sure you are looking in the correct category. Bible translations cannot be opened in this second screen. 

Choose the commentary you want. 

When you select the "synchronise" boxes, the top one turns blue. 

You can download or purchase more commentaries in the store in the app. You can find a link to the store at the bottom of the list of available titles.