I understand how auto commands work, and how to use them, but I'm a little bit sure of what augroup is for. I read in :help augroup                                                    *:aug* *:augroup*:aug[roup] {name}               Define the autocmd group name for the                                following :autocmd commands.  The name end                                or END selects the default group.                                To avoid confusion, the name should be                                different from existing {event} names, as this                                most likely will not do what you intended.This doesn't really explain why they are useful, or why I would ever want to make an autocommand group name over just defining a bunch of autocommands next to each other. For example, if autocommands foo and bar are related, why would I want to doaugroup spam  au!  au foo * foo  au bar * baraugroup ENDwhen I could just doAutocommands for spamau foo * fooau bar * barUnless I'm misunderstanding what augroups are really for. So why are they useful?
Why should I use augroup?
autocmd
The main reason to use augroups is to allow greater control over ranges of autocommands, e.g. to delete a bunch of autocommands in one go. A common pattern is to use the au! as the first part of a group. This removes all existing autocommands in the group, and allows one to start afresh. If you did not use a group, then au! would remove all/many autocommands that you did not want to remove.Deleting autocommands is actually quite common, for instance in plugins, because this allows one to source a plugin/ftplugin multiple times. If you did not delete the autocommands, then each time you sourced the plugin/ftplugin you would add a new copy of the same autocommand. This is also true for your vimrc file. By using a group in your vimrc file, it becomes safe to reload it.For more info, see :h 40.3.