A sector is an area of space framed by an artificial boundary for political, economic and military organization.
The Directorate of the Valcarian Republic was the first body to attempt an large scale application of standardized sectors. A sector was defined by the Republic as having a maximum of 50 inhabited star systems to keep sectors at a manageable level. The rapid exploration, expansion and colonization caused many sectors to grow larger than the intended size.
When the Valcarian Empire took control of the Republic's sectors, Imperial Grand Governors replaced senators as sector governors. Sectors were also commonly expanded and collapsed together to consolidate power in the officers delegated by Altharra to rule.
Many sectors owe their name to their primary system which in turn was named after its primary planet. For example the planet Aernys belongs to the Aernys system and this, to the Aernys Sector.