The Suttavibhanga is the first part of the Vinaya Pitaka ("Basket of Discipline").
The Vinaya Pitaka is the first part of the Tipitaka ("Three Baskets"), a.k.a. the Pali Canon.
The Tipitaka is the major religious text of Theravada Buddhism.
From 'do not poke another bhikkhu (monk) with your finger' to 'do not deprive any living being of life', this section of the Tipitaka deals with how to keep a Sangha (Buddhist monastic order) running smoothly. Despite the fact that the Dhamma (teaching of the Buddha) stresses freedom and self reliance, a community relying on donations for survival needs some rules to keep everyone from strangling each other. In laying down the rules, the Buddha gave ten reasons for each rule: "for the excellence of the Community, the peace of the Community, the curbing of the shameless, the comfort of well-behaved bhikkhus, the restraint of pollutants related to the present life, the prevention of pollutants related to the next life, the arousing of faith in the faithless, the increase of the faithful, the establishment of the true Dhamma and the fostering of discipline." The Buddha did not just give out the rules in the Suttavibhanga, though; he also used many models and principles common to his teachings so the basis of the rules could apply to many situations.
The rules were also not laid down all in one go, but rather one by one in response to particular incidents. The situations behind each rule can help in understanding the reason for and underlying concepts of each rule: for instance, the rule forbidding 'wrongful contact' between bhikkhus and women seems to imply that women are of a lesser state or lesser importance than bhikkhus, but upon examining the background story, it becomes apparent that the rule is intended to ensure that women need not worry about molestation or other forms of harassment from the sexually deprived bhikkhus. The stories behind each rule can be found in the Khandhakas, the two books making up the second part of the Vinaya Pitaka.
As time went on, the number of rules slowly grew, and a Sangha led by the Venerable Upali organized them into one work. The rules in the Suttavibhanga are divided into seven groups, organized from most serious to least serious. Punishment for each offense is aimed not at actually punishing the offender, but rather to help the offender realize the error of his ways and prevent the situation from occurring again. Accidental infringements of certain rules (such as imbibing alcohol) are treated no differently than purposeful infringement, but are considered a much less serious offense
(such as killing an animal). "If a monk breaks one of the four most serious rules — the parajikas — he is expelled from the Community for life. If he breaks one of the next most serious classes of the rules — the sanghadisesas — he is put on probation for six days, during which time he is stripped of his seniority, is not trusted to go anywhere unaccompanied by four other monks of regular standing, and daily has to confess his offense to every monk who lives in or happens to visit the monastery. At the end of his probation, twenty monks have to be convened to reinstate him to his original status. The next three levels of rules — nissaggiya pakittiya, pakittiya, and patidesaniya — entail simple confession to a fellow monk, although the [nissaggiya pakittiya] rules [involve] an article that has to be forfeited — in most cases temporarily, although in a few cases the object has to be forfeited for good, in which case the offender has to confess his offense to the entire Community."1
If a bhikkhu refuses to go through with the punishment, it is up to the Sangha to determine what to do. The Sangha will often try to help the offending bhikkhu realize his error and help him learn from the situation, removing seniority or suspending him from the Sangha for a period of time — if this is successful, the bhikkhu is returned to his former position. If it does not work, there is no further punishment save for expulsion from the Sangha (for serious offenses) or removal of all status while keeping him in the Sangha (for less serious offenses), in the hopes that he may one day come clean. As there is no higher authority of punishment except for one's conscience, offenses may go unknown forever. However, the cycle of karma ensures that no one really "gets away with" anything in the long run. The last two sets of rules do not give explicit methods of punishment, as they deal mainly with etiquette, and are generally considered to be principles to try to work at following.
The eight parts of the Suttavibhanga, along with an introduction, are referred to as the Patimokkha. The first version of these texts was as a discourse read aloud at a meeting of bhikkhus held twice a month, during which any bhikkhu who had committed any of the offenses would come forward, admit the offense and, if need be, begin the punishment. However, the Patimokkha also contains a set of rules relating specifically to bhikkhunis (Buddhist nuns), as the contents of the Suttavibhanga deal mainly with bhikkhus (although the gender of the student does not matter for many rules).
"[E]very single Rule or Clause in the Pâtimokkha is in fact [f]ound word for word in the Sutta-vibhanga, the quotations being so complete that the Pâtimokkha might be entirely put together again by piecing together extracts from the Vinaya Pitaka. And it is not possible that the Pâtimokkha originated merely by such a process of dovetailing; for the quotations in the Vinaya Pitaka, though not actually called quotations, bear the unmistakable stamp of being taken from some pre-existing work. The cause which led to the Pâtimokkha, and the Upasampadâ-kammavâka, being separately preserved at all, is the same as the cause which led to their exclusion from the lists of the Pitaka texts—the fact, that is, of their being liturgical compositions."2
Information/interpretation from personal experience, (1:) Thanissaro Bhikkhu's "Introduction to the Patimokkha Rules," available at http://www.accesstoinsight.org/canon/vinaya/bhikkhu-pati-intro.html and (2:) "Introduction to the Vinaya Texts from the Pâli," available at http://www.sacred-texts.com/bud/sbe13/sbe1302.htm. Text in "double quotes" is a quotation from one of those texts; text in [brackets] within one of those quotes has been added to clarify a point or to correct a typographical error.