/etc/environment - contains a list of variables and is the first file that is processed while starting bash. It is empty by default on RHEL
/etc/profile - is executed while users login
/etc/profile.d/ - is used as a snapin directory that contains additional configuration
~/.bash_profile - can be used as a user specific version
~/.bash_logout - is processed when a user performs logout
/etc/bashrc - is processed every time a subshell is started
~/.bashrc - a user specific version may be used