Rabbi Aryeh Kaplan, Handbook of Jewish Thought, Volume 1, pp. 236-238 – After the closing of the Talmud, the Gaonim carried on the unbroken tradition.
The main work of the Talmud came to an end with the death of Ravina in 4259 (499 CE). This initiated the period of the Savoraim (Rabbanan Savorai), who made some final edits and comments to the Talmud and added a few passages of their own. The period of the Rabbanan Savorai lasted 90 years, until 4349 (589 CE). In some places, they wrote final decisions about halachot disputed in the Talmud. Since the Savoraim headed academies including all the Sages of the time, their decisions are as binding as those of the Talmud.
This was followed by the period of the Gaonim, which lasted until the death of Rav Hai Gaon in 4798 (1038 CE). A Gaon is the head of either of the great academies of Sura and Pumbadita in Babylonia, which had been founded in Talmudic times and were still considered the centers of authority in all matters of Torah law. To qualify, the Gaon had to have absolute mastery over the entire Talmud.
The decisions of the Gaonim were almost universally accepted. Therefore, they cannot be disputed by any later authority without considerable proof.
...As the great Babylonian academies diminished in stature, there ceased to be any formally acknowledged world center of Torah authority. However, a number of summaries of halachic decisions based on the Talmud and the rulings of the Gaonim were compiled by leading rabbis, and they achieved almost universal recognition. Most noteworthy among these were the works of Rabbi Yitzchak Alfasi (Rif; 1013-1103 CE), Rabbi Asher ben Yechiel (Rosh; 1250-1328 CE), as well as the Mishnah Torah, or Yad HaChazakah, by [Rabbi Moshe ben Maimon, or the] Rambam (1135-1204 CE). The rabbis of this period are known today as the Rishonim, the “earlier [Torah authorities].”

Rabbi Moshe Mizrahi, HaKeter Institute, Jerusalem – The roles of the Rif, Rashi and Rambam.
Of course, every word in the Talmud is necessary, but the lengthy back-and-forth discussions made it difficult and cumbersome for all but the most advanced scholars. To remedy this, the leading Spanish Torah scholar of his time, and maybe of all time, Rabbeinu Yitzchak Alfasi (Rif), wrote a condensed version of the Talmud, leaving out all its discussions and giving the reader the conclusion and final decisions. A student of both Rabeinu Nissim ben Yaakov and Rabeinu Chananel, Rav Alfasi’s work became the prime source for halachah. Every halachic work produced since then has been influenced by it, and it is printed together with every edition of the Talmud.
At the same time in France, Rabbeinu Shlomo ben Yitzchak, or as we know him “Rashi,” sought to make the Talmud more accessible in a different manner. He composed a running commentary on the entire Talmud, deciphering difficult words and explaining the Talmud’s discussions in a brief but comprehensive manner. Almost all of his commentary is extant today, and it has become so basic and popular that there is no longer such a thing as studying Talmud without Rashi’s commentary. Even so, with few exceptions, Rashi did not give us his opinions about deciding the halachah where it is disputed or undecided in the Talmud.
In the following century, another Spanish scholar, Rabbeinu Moshe ben Maimon [Maimonides, or Rambam], came up with a revolutionary idea. He saw that the halachot were scattered haphazardly throughout the Talmud, so that if someone wanted to master the halachot of Shabbat he would have to know tractates Bava Kama, Ketubot, Pesachim and others besides the basic tractate of Shabbat. So he began a ten-year project to gather all the halachot found in the Talmud and organized them in a clear fashion. Also, taking into account that the Jews no longer lived in Babylonia, he rewrote all the halachot of the entire Oral Torah, taken from the two Talmuds and the responsa of the Gaonim, in clear, classic Hebrew, a language that he expected Jews in all countries to understand. He named this work Mishneh Torah, which means the “Repetition of the Torah.”

The Shulchan Aruch - This 16th-century text by Joseph Caro is the ultimate code of Jewish law
Rabbi Jill Jacobs, MyJewishLearning.com
Given the Talmud’s complexity, scholars since the medieval period have attempted to codify Jewish law in an easily accessible format. In the 12th century, Moses Maimonides (Rambam) composed the Mishneh Torah, a summary of laws relating to all areas of Jewish life. This work, written in simple Hebrew, is meant to be accessible for the average Jew who does not have the skills or motivation to access Talmud.
A century later, Jacob ben Asher produced the Arba’ah Turim (often called the Tur for short), a code that addresses only the practical areas of Jewish law. Unlike Maimonides, Jacob ben Asher restricted his discussion to laws relevant to post-Temple Jewish life, and cited his sources, referencing different opinions when necessary.
The Shulchan Aruch’s Beginnings
On the heels of the Tur, the next influential Jewish code of law was the Shulchan Aruch (literally, the “set table”), written by Joseph Caro (1488-1575). Caro was part of a Sephardic family that was expelled from Spain in 1492. After the death of his father, Caro was adopted by his uncle, Isaac Caro, the author of a commentary on the Bible. The Caro family eventually settled in Safed, the area of northern Israel where the mystical circle of Isaac Luria then flourished. Both Isaac and Joseph Caro became part of this community of mystics.
Joseph Caro originally set out to write a commentary on the Arba’ah Turim that would cite sources not mentioned by Jacob ben Asher and that would often differ from the Tur’s conclusions. This commentary, named the Beit Yosef, reads like a set of footnotes to Jacob ben Asher’s more concise statements of law.
In the introduction to this work, Caro explains that the expulsion of the Jews from Spain and their subsequent dispersion among Ashkenazic communities had caused confusion about the rules of observance. Sephardic Jews often found that their inherited traditions differed from those of the Ashkenazi Jews into whose communities they had moved; with the dismantling of Sephardic communities, it was no longer clear who had authority to decide matters of law. By presenting all known sources on particular issues, Caro hoped to clear up this confusion.
The Beit Yosef eventually became the notes for the Shulchan Aruch, which would become Caro’s most famous and influential work. Originally intended as a crutch for those not sufficiently learned to read the Beit Yosef or the halachic works referenced there, the Shulchan Aruch soon became the most important code of Jewish law.
Format of the Shulchan Aruch
Caro divided his work according to the categories introduced by Jacob ben Asher. Like the Arba’ah Turim, the Shulchan Aruch is divided into four sections:
Orah Hayim (laws relating to prayer, Shabbat and holiday observance, and other rituals of everyday life),
Yoreh De’ah (laws of kashrut, tzedakah, conversion, and other ritual matters),
Even ha’Ezer (laws relating to women and marriage), and
Hoshen Mishpat (civil law, including sections on lending money, renting and buying homes, and worker-employer relations).
Within each of these four sections, laws on similar subjects are grouped together. Each section is divided into simanim (paragraphs), and those are further divided into se’ifim (sub-sections). A citation of the Shulchan Aruch, thus, might read: Hoshen Mishpat 335:1, meaning: section Hoshen Mishpat, siman (chapter) 335, se’if (item) 1.
In general, the Shulchan Aruch presents laws in a straightforward way, with virtually no discussion. For example, Caro’s instructions for lighting Hanukkah candles read:
"How many candles should one light? On the first night, one lights one; from then on, one adds one each night until there are eight on the last night (Orah Hayim 671:2)."
Although the Talmud and other earlier texts include other traditions for the appropriate means of lighting Hanukkah candles, Caro chose to present only what he considered to be the correct procedure, in order to avoid confusing his readers.
Commentaries on the Shulchan Aruch
When Caro published the Bet Yosef, Rabbi Moshe Isserles (known as the Rema), an Ashkenazi legal scholar, responded with his own commentary on the Arba’ah Turim, called Darkhei Moshe. Learning that Caro was about to issue the Shulchan Aruch, Isserles abandoned this project and instead wrote a commentary on Caro’s work.
Isserles criticized Caro for often ignoring the opinions of Ashkenazic scholars, commenting that, “Caro’s books are full of decisions that do not follow the interpretations of the sages from whose waters we drink …[the sages] whose children’s children we are.”
The Rema's contribution (from Prof. Eliezer Segal's website)
Isserles perceived a serious shortcoming in Caro's work, in that it was based almost entirely on Spanish (Sepharadic) authorities. Of the three principal pillars of the Shulhan Arukh [the Rif, the Rambam, and the Rosh], only the Rosh had non-Sepharadic roots, having lived most of his life in Germany before moving to Spain. However his legal compendium had been written in the the Spanish spirit.
Thus it was evident that, in spite of its great virtues, the Shulhan Arukh could not be accepted by Jewish communities in Germany and Poland without some modification. Isserles sought to perform this service with his glosses, in which he supplemented the rulings of Caro's original Shulhan Arukh with material drawn from the laws, interpretations and customs of Franco-German and Polish Jewry.
All standard printed editions of the Shulhan Arukh include Isserles' notes, embedded in the text (introduced as "Hagahah ["gloss']), but distinguished by its semi-cursive ("Rashi") script. When people refer to the "Shulhan Arukh" they are usually thinking of the combination of Caro's and Isserles' works.
[The Growing Acceptance of the Shulchan Aruch]
It has become a familiar joke that every time a person claims to have the last word on Judaism, multiple commentators appear to challenge this assertion. Famously, Maimonides had the chutzpah to claim that a person could read the written Torah and then the Mishneh Torah and “from them, know the oral Torah and have no need to read another book.” Not surprisingly, Maimonides’ code did not become the last word in Jewish law, but rather almost immediately became the subject of numerous commentaries and critiques.
Similarly, the Shulchan Aruch did not immediately achieve widespread acceptance. Many scholars thought publishing a comprehensive code of law was forbidden, fearing that readers of such a code would have no way of knowing the history or range of opinions on various laws.
Rabbi Shlomo ben Yechiel Luria (the Maharshal), a contemporary of Caro’s, was the author of Yam shel Shlomo, a commentary on part of the Talmud. In the introduction to that work, the Maharshal declared the impossibility of “explain[ing] every uncertainty in the Torah to the point that there is no disagreement.” Rather, he argued, each scholar should delve into the sources, add new interpretations, and decide among various opinions.
Ironically, the Shulchan Aruch ultimately gained its legitimacy through the publication of two major commentaries by 17th-century Ashkenazic scholars. These works, known as Turei Zahav (“Taz”) and Siftei Kohen (“Shakh”) and written by David ben Shmuel haLevi (Poland, 1586-1667) and Shabbetai ben Meir haKohen (Lithuania, 1621-1662), respectively, respond to the critiques of the Shulchan Aruch by explaining Caro’s reasoning, introducing alternative opinions, and offering their own conclusions.
In treating the Shulchan Aruch as an independent work worthy of a commentary of its own, rather than as the poor cousin of the more extensive Bet Yosef, these two scholars secured the place of the Shulchan Aruch as the authoritative code for generations to come.
The best-known later commentary on the Shulchan Aruch is the 19th-century Mishneh B’rurah, written by Yisrael Meir Kogan, which includes explanations and a collection of later opinions on the Orah Hayim section of the code. The 19th century also saw a number of attempts to abridge the Shulchan Aruch. The most famous of these is Shlomo Ganzfried’s Kitzur Shulchan Aruch, which summarizes Caro’s work while also incorporating some alternative opinions and contemporary customs.
Influence of the Shulchan Aruch
To this day, the Shulchan Aruch remains the most influential code of Jewish law. Contemporary legal scholars may, on occasion, disagree with Caro’s conclusions, but they cannot ignore him. The proliferation of commentaries on the Shulchan Aruch has only solidified its central position in the canon. Almost 500 years after Caro produced a work intended primarily for those unable to study more complex legal works, his code has become the primary textbook for most traditional Jewish schools and yeshivas.