Quickly:

Based on: nginx

Tagging:

** '.rtmp'** in the tag means, this version of nginx image has the 'rtmp' module.

'.netfree' in the tag means the Netfree⁠ SSL certificate/s, related ENV variables and/or config files etc. is embedded, so the image is prepared to work in Netfree environment.
Netfree is working with multi internet providers. So, each image tag describes which provider/s is supported, by the label internet-providers.

Without any kind of warranty.