Source lets you add external files/code into your scripts, but is also a convenient way of adding config files, providing you are aware of the risks.
The benefits are that source is extremely quick to run, with memorable syntax.
The risks are that all code in the file(s) you source will be executed, even if you only anticipated the file holding variables.
In short, if there's any chance of anyone else adding/editing the config files (a curious user, perhaps), then source isn't the right option.
Let's say you have a config file (config.ini) that contains your_var=your_val.
In your script, you can use source or the shorthand . syntax
. config.ini
# or: source config.ini
echo $your_var
>>> your_valBut if anyone can edit config.ini, and they add executable commands... Well just hope they are messing with you and add a relatively painless reboot, rather than rm -rf /. You've been warned!