So what exactly IS a Hold?
The Holds of Pern are where the majority of people on Pern live. Holds are literally castles, just not quite like the castles from the Middle Ages. There are three sizes of Hold: Major, Minor, and Cothold. Major Holds are ruled by a Lord and Lady Holder, and their family, and are generally passed down in a hereditary fashion. The remainder of the residents are staff and workers who run the hold, and professional crafters; all told, they usually number around one thousand. The Headwoman is in charge of the inner hold, and looks after all of the workings inside, while the Steward runs the outdoor parts of the hold. Major Holds tithe a portion of their produce to the nearest Weyr in return for protection from Thread. In times where there is no Thread, however, it is not uncommon for Holds to become grumpy, and try to refuse to tithe, especially if they don't believe thread is returning. This causes stress between Weyrs and Holds, and sometimes causes problems for both parties, including fights between people with different viewpoints, and sour relationships between Weyrs and Holds.
Minor Holds are always beholden to a Major Hold, and tithe to them in return for protection from Thread and other dangers. They are run by a person who bears the title of Holder, and are home to smaller numbers of people than Major Holds. Many Seaholds are Minor holds, dotting the oceanfront for it's fish.
Cotholds are small, family-run holds, and usually all those who live there are family or close friends. 'Family' on Pern generally means an extended family of several generations and branches, as opposed to the nuclear family common in Western societies on our own world.
Each hold is responsible for the discipline of its wrongdoers. Most times the Lord Holder will make the wrongdoer pay restitution and service to the wronged party. The next level of punishment is incarceration. Death penalty can also be used in response to heinous crimes. One of the greatest punishments is to be named holdless. This is where a person is stripped of all rank and status and thrown out of the hold. The most severe punishment of all is exile, usually to the island archipelago known as the Eastern Ring Islands. The reason this is the most severe punishment is because the holdless have nowhere to go during Threadfall and have no other human contact. This punishment is usually followed by a Shunning, which, in effect, causes the Shunned to be ignored completely by all humans. It is established in Dragon's Fire that the holdless are marked on their foreheads with an indelible dye for identification.
A Hall, however, is different. The Crafthalls are the home to craftsmen; those Pernese skilled in a particular industry. The Crafts of Pern are: Harper, Smith, Healer, Miner, Weaver, Farmer, Fisher, Tanner, Baker, Vintner, and Herder. For example, the Harper Hall is responsible for the arts (specifically music) and teaching young children the Teaching Ballads, which provide them with basic knowledge. When a child is ten or twelve, they can be sent to be an apprentice at a Crafthall if they show a flair for that particular craft. The Crafthalls train the crafters and send them out all over Pern to provide their skills to even the remotest hold. Note that it is not necessary for someone to be (for example) a trained farmcrafter in order to grow food; holders have a wide variety of skills, but it is the crafters who are the experts.
The crafts all use the same hierarchy. Everyone in each craft begins as an apprentice, usually from age twelve to eighteen, then becomes a journeyman (eighteen to thirty) with a great deal of hard work and dedication, attainment to the status of Master (thirty+) is possible. Not everyone makes it to Master, and some leave before even the rank of Journeyman is reached. Such a step from apprentice to journeyman is called 'walking the tables', based on the custom that apprentices and journeymen eat at different tables at a crafthall. The craft rank and hold they are beholden to are indicated by complicated knots which are worn on the shoulder.
The crafthalls are located near or in the Major Holds, with at least some crafts having local crafthalls at other Major Holds.
The leaders of the Halls are called Mastercrafters, for example, the Masterharper is the head of the entire Harper Hall, and is not to be confused with a Master Harper, of which there may be several.