From maven.apache.org, Naming Conventions:
artifactIdis the name of the jar without version. If you created it then you can choose whatever name you want with lowercase letters and no strange symbols. If it’s a third party jar you have to take the name of the jar as it’s distributed.
groupIdwill identify your project uniquely across all projects, so we need to enforce a naming schema. It has to follow the package name rules, what means that has to be at least as a domain name you control, and you can create as many subgroups as you want. Look at More information about package names.