The Third Degree in Freemasonry is the culmination of the preceding two degrees, and is considered the highest degree in Freemasonry; there is none more important.
Masonic degree rituals teach lessons of morality and personal honor, and ask the candidate to swear to conduct himself accordingly. The rituals are supposed to be solemn and insightful ceremonies and are not degrading or demeaning to the candidate, his morals or his personal beliefs.
As with many ritualistic fraternal organizations, the ritual is one of the few things about Freemasonry that is supposed to be secret, because it includes the words and signs used for Masonic recognition. There have, however, been a great many "exposures" of those rituals, starting shortly after the first Grand Lodge was formed in the early 1700's. Some of these exposures have been accurate, for their time, and some have not. The point of many of them was to discredit the Fraternity, and so some are very fictitious. Most that are available today are from the 19th century or earlier, and though they may be similar, they do not properly reflect the rituals in use by the vast majority of Masonic Lodges today.
If you are considering becoming a Freemason, I urge you to avoid spoiling the experience by looking at the various versions of the rituals beforehand.