Gunnery has two main mechanics directly tied to it: Hit chance and turret damage. These two are linked together on many levels and having a basic understanding on the mechanics is important for anyone who flies a turret based ship in EVE.

Hit chance

range

Tracking

Damage

Skills

Practical applications

References

http://forum.eveuniversity.org/viewtopic.php?p=201888#201888

http://forum.eveuniversity.org/viewtopic.php?p=216525#p216525

http://www.hostile.dk/files/eve/eve-tracking101.swf

https://www.reddit.com/r/Eve/comments/5h24bk/turrets_listed_signature_resolution_is_40km/