bash is the default shell application on NREL HPC systems and the terminal environment on many operating systems.
Bash has a lot of quirks; even for the experienced Bash wizard, there are a lot of caveats and odd syntax details to remember. There is a nice introduction and a diagram of how the kernel, shell, and applications relate here. A more thorough treatment may be found at tldp.org. There is also a very brief history of UNIX shells for context.
Afterwards, please see this very thorough and concise cheatsheet that documents most of Bash's features.