Louis XVII did not do much by himself and he was not very important in the events of the French Revolution except if you want to take a very close look at the royalist movements the royalist/counter-revolutionary political aspects. This is why he is rarely, or even never, mentioned in history classes.

Louis-Charles was the second son of Louis XVI and Marie-Antoinette. He became Dauphin (heir) of France in 1789 after his older brother Louis-Joseph died in June 1789 after a short life of diseases. In 1792 when the royal family was arrested, Louis-Charles was sent to Temple prison in Paris. He never got out until his death in 1795. When Louis XVI was executed on 21st January 1793, Louis-Charles became the new king in the eyes of the royalists, as Louis XVII. It was in name only except for the royalists who refused to consider that the throne was vacant. Traditionally, the king of France never dies and the throne is never unoccupied. As soon as a king dies his successor his proclaimed (the king is dead, long live the king). So it is said that when Marie-Antoinette heard the canon fire in Paris on the 21st of January, she knew her husband was dead and she knelt in front of her 7 years old son. She remained with him until July of the same year, at this point they were separated and this until Marie-Antoinette's death in October. He was asked to testify against his mother when the court brought the case of incest relations between he and the former queen, which he did.

The two following years were spent in an almost total seclusion except from seeing (very rarely) his sister and his "teacher" a revolutionary called Simon. After that, nobody really came to see him, except the general and deputy Paul Barras who wanted to see in "what" physical and mental state Louis-Charles was. He died in June 1795, officially of tuberculoses and an other disease.

What happened to him is subject of debate. There are of course the stories that he escaped, that he was freed by royalists (I even read one story saying that Robespierre freed him) and lived in a foreign country. Several cases of people claiming to be him or a descendant exist, some DNA tests were even made recently. The most famous case being that of the Naundorff family, who were even send to court in the early 20th century for their use of the Bourbon name which was not appreciated by members of the "real" Bourbon family. Those are of course false stories, made by romantics or royalists in the 19th century. But still, the conditions of his seclusion are not very well know. Was Antoine Simon, his "teacher", the awful man painted by royalists, who abused him ? We can't be sure. But poor conditions, a very traumatic life (the last two years spent alone, as an orphan) certainly destroyed his health and killed him.

What to do of him was a difficult question for the revolutionaries. He could not really be freed and given to a foreign power like his sister Marie-Thérèse was about to be. Many royalists, especially in the Chouannerie and the Vendee were fighting in his name and he could be a potential threat for the future of the Revolution. He could not be executed, and it is doubtful that many people were in favour of such an action, as it would probably not please public opinion or foreign powers. So he remained in the temple, and before any decisions about his future were made he died. In 1795, Louis XVII's uncle and heir, the count of Provence, took the name Louis XVIII and dated June 8th 1795 as the beginning of his reign.

Today there are no real doubt left about his fate and those claiming he survived the Temple are a bit off. The heart of the body found during the Restauration was analyzed and confirmed to be his, even if it is true that DNA analysis include several issues about authenticity.

I hope this helps. So all in all he was not that important if you simply study the events of the Revolution. However Louis XVII is an important figure in the development of royalist political culture for exemple. And of course his tragic fate has everything needed for a good story, and for conspiration theories. The memory of the Dauphin was used again and again in fightings by and against royalists (the young martyr, etc.) which created a myth around him. Also, historians studying the history of children rights and/or education will found Louis XVII very interesting, as an example of a child who was stuck between conflicting ideologies and between wars.

Louis XVI by Bernard Vincent

Louis XVI by Evelyn Lever

L'Affaire Louis XVII by Philippe Delorme