During the 9th century C.E., a number of sects arose that denied the existence of oral Torah. These sects came to be known as Karaites (literally, People of the Scripture), and they were distinguished from the Rabbanites or Rabbinical Judaism.
The Karaites believed in strict interpretation of the literal text of the scripture, without rabbinical interpretation.They believed that rabbinical law was not part of an oral tradition that had been handed down from G-d, nor was it inspired by G-d, but was an original work of the sages. As such, rabbinical teachings are subject to the flaws of any document written by mere mortals.
The difference between Rabbanites and Karaites that is most commonly noted is in regard to the Sabbath: the Karaites noted that the Bible specifically prohibits lighting a flame on the Sabbath, so they kept their houses dark on the sabbath. The Rabbanites, on the other hand, relied upon rabbinical interpretation that allowed us to leave burning a flame that was ignited before the sabbath. Karaites also prohibited sexual intercourse on the sabbath, while Rabbanites considered the sabbath to be the best time for sexual intercourse. The Karaites also follow a slightly different calendar than the Rabbanites.
According to the Karaites, this movement at one time attracted as much as 40 percent of the Jewish people. Today, Karaites are a very small minority, and most Rabbinical Jews do not even know that they exist.
Sources: Judaism 101