DNN only knows view and edit permissions for modules.
I think however a lot of people would require more options like add and/or delete permissions.
Let's say you've built a website, and you want to give someone access only to edit texts, but not to delete the module.
How are you going to do that?

I am sorry, but though Leo is correct (modules can provide individual permissions like UserDefinedTable/formAndList module does), this doesn't cover permissions to enter settings, permissions or delete the module.

By design, only people with Edit permission for the page are allowed to add/delete/configure a module. There is a glitch in DNN 5.1.0 CE, granting access to module settings to users with edit module permissions.

DNN 5.1.0 also introduces a permission provider, allowing for more granular configuration. There are still some details to fix, but future versions will be able to use a provider implementation with additional options and DNN PE will provide this option out of the box.

For more granular permissions you need DotNetNuke PE or a custom/3rd party permission provider.