Who is the Rambam? [duplicate]

Question

The name Rambam appears often in answers and it seems his opinion is highly regarded.

Who is this Rambam figure and why should people consider answers referencing Rambam as possessing religious authority?

Answer 1

Britannica explains who the Rambam is in a nutshell

Moses Maimonides, original name Moses ben Maimon, also called Rambam, (born March 30, 1135, Córdoba [Spain]—died December 13, 1204, Egypt), Jewish philosopher, jurist, and physician, the foremost intellectual figure of medieval Judaism.

His first major work, begun at age 23 and completed 10 years later, was a commentary on the Mishna, the collected Jewish oral laws. A monumental code of Jewish law followed in Hebrew, The Guide for the Perplexed in Arabic, and numerous other works, many of major importance. His contributions in religion, philosophy, and medicine have influenced Jewish and non-Jewish scholars alike.

The Rambam is particularly quoted here as his major work of Jewish Law, the Mishne Torah, reorganizes all the law found in the Mishna and Talmud and structures it by topic (see here). This was a monumental undertaking (esp. in pre-digital days) which enabled people who weren't able to learn or memorize the Talmud to know what Jewish law says about any topic. Unlike some later codes of law, the Mishne Torah also ruled on laws not practiced since the destruction of the Temple (e.g., sacrifices).

The Mishne Torah is widely acknowledged by all segments of Jewry and forms one of the three key sources that the Shulchan Aruch used later on to write his code of law (which itself became the standard for many other works).

See also here and here. And if you are interested in the history of halacha, see here p. 6 where the Rambam's role is described at length ("probably the greatest scholar and personality of the period of the Rishonim [who] wrote the most important halachic code of this era.")

Answer 2

Rambam (1138-1204) was a Jewish sage and a big rationalist. Here is a good summary of the Rambam.