Household
Households Defined
Broadly, an SCA household is a group of people who are friends who gather together for mutual support or interest.
Typically, a household will hang around together at day events and camp together at camping events. There can be as few as three members or as many as several hundred. They might call themselves a household, a ship, or a clan.
Households can vary just as much in focus as in size. They may just be a grouping of friends and/or family, or a peer and their students. A household might focus around a theme - like a nautical ship, 14th Century English, or non-European personnas. They might center around an activity or two, such as archery, a war band, partying, or service. They could be created for a specific area - a shire, barony, or the like, or perhaps they span many areas, or even many Kingdoms. Organization will vary significantly as well - there are no specific defined rules or required structures. Some households have almost none, while others may have detailed rules, traditions, officers, and so on - to the point of operating very similarly to an official SCA branch, without being one. Also, much like the people they are made up of, households may change over time.
Ducal Households
As is customary in An Tir, those of Ducal rank (Duke or Duchess) may create for themselves a Ducal Household of retinue (personal herald, guard, ladies-in-waiting, etc.) which are recognized by the Crown. All those of Ducal rank may hold Ducal Audiences or Courts. They may not grant any awards, but they may give tokens and scrolls of praise and recognition.
Unofficial Status
Households don't have any official status in the SCA. You don't have to get anyone's permission to form one. Households come and go. They are a natural and recognized part of SCA life.
Despite this, you may find many references to households in official SCA publications. For example, event copy ("Gate volunteers supplied by House Grindstone"), and on the Order of Precedence - households can be, and have been, given awards.
Further Reading
More general information about SCA households: http://sca.4th.com/justin/articles/households-intro
For a list of households on the wiki, see Category:Household.