Youma (Demons) are demonic beings that prey upon humans. They feed on their internal organs, often while their victim is still alive. To conceal their identity they can pass off as a townsfolk if they are hiding within a village. They generally consider themselves superior to humans in every way possible, and while it is possible for a human with reasonable strength to kill a Youma, the problem then becomes finding them.
Claymores and the Organization
The Organization was founded on the premise of combating the threat of Youma that terrorize the many villages and towns of the mainland. To that end, they create hybrids, half-demon half-human warriors who take in the blood and flesh of the Youma and become what the people refer to as Claymores. Most Claymores are taken in as orphans and slaves, thus it is rare for anyone to willing go to the Organization to become one. The first generation of Claymores were male for the most part, but males proved unable to suppress their Youma auras, thus all generations from there on were women only.
To finance their operations, Claymores are often dispatched to various villages and towns to eliminate a/many Youma that have made their way into a society and Claymores carry unnatural strength, speed and regenerative powers, and are essentially superior to a Youma in all aspects, but their greatest asset is their ability to sense Yoki (the aura of Youma energy that all Youma/Claymores carry) and determine who in a group of people is a Youma in disguise.
The organization is known for conducting a variety of unethical and controversial experiments and procedures in order to obtain their goals, including the conditioning of Alicia and Beth to align themselves and execute their "Soul Link" technique, using a fallen warrior's flesh and blood on Clare, instead of a Youma's, the treatment of their trainees and warriors, where they often suffer high casualties and many other things.
One of the greatest hidden truths of the Organization is ultimately they end up creating the very beings they are supposed to hunt. All Claymores carry within them the essence of a Youma and drawing upon their strength for too long a period or too much energy at once will push a Claymore beyond their limit and they will awaken into a being that is Youma, but far beyond the abilities of either a Youma or a Claymore. They become an Awakened Being, holding onto their memories and skills, while their normal personality is replaced with a bloodlust and a need to consume human innards.
Rank System and Emblems
A Claymore who graduates from their training (assuming they survive) is assigned an emblem and a number rank. To assign each territory 1 Claymore, the Organization normally has 47 Claymores on dispatch/patrol at nearly any given time. Some die, get replaced, but often 47 is the maximum they have on the field. Within the 47 warriors, there is a numbered ranking system which, while is not 100% absolute in determining who is the strongest warrior (As shown by half-awakened warriors, for instance), it is often seen as a reliable means of implying who is the strongest (#1) and who is the weakest (#47). Often warriors who are ranked in the lower 30's and 40's are viewed as weak by the other members, and are considered less reliable on the battlefield. The organization does little to practice such discrimination between all 47 warriors, as they normally consider all 47 to be expendable (with the only recent exception being Alicia and Beth).
Luciela was #1 and Rafaela was #2 of this time, just prior to Teresa's Time. No other Claymores were mentioned during this brief period of the storyline. These two were part of experiment by the Organization to undergo a "Soul Link" where one would purposely awaken while the other would hold onto her "Spirit". The experiment failed and Luciela permanently awakened and nearly destroyed the entire organization. Rafaela was stripped of her rank and emblem and she would not return to the organization until Clare's Time.
This timeline is considered important in the series since it covers when Clare (the main protagonist of the series) meets Teresa, the most powerful #1 Claymore ever, and the events that lead up to Clare willingly joining the organization on her own.
Where most of the series takes place, so we get a good look at a majority of the warriors of this time, though the focus of the story is on Clare herself. The most number of warriors we see at once draws close to the end of this timeline where 24 Claymores are dispatched to the Northland town of Pieta to deal with a major threat.
7-Year Time Skip
The most recent addition to the series in the manga only. This takes place 7 years after the battle of the Northlands. For the most part, the story focuses on the survivors more on the organization, so there is limited information on the orgnization members.