Devices can be character devices (like keyboards and serial ports), block devices (such as hard disks and USB devices), network devices (e.g., eth0) and virtual devices (like /dev/null).

In this excerpt, Chapter 9, from the book, the author describes how kernel device drivers interact with system hardware and how developers can write device drivers and use them in their applications.

The blkid command displays block device attributes. It shows the 128-bit UUID and file system type, but it is not likely to be the most illuminating command for providing partition stats.