<P> The 100 (pronounced The Hundred) is an American post-apocalyptic science fiction drama television series developed by Jason Rothenberg, which premiered on March 19, 2014, on The CW . It is loosely based on a 2013 book of the same name, the first in a book series by Kass Morgan . The series follows a group of teens as they become the first people from a space habitat to return to Earth after a devastating nuclear apocalypse . </P> <P> In March 2016, the series was renewed for a fourth season of 13 episodes, which premiered on February 1, 2017 . In March 2017, the series was renewed for a fifth season . As of May 24, 2017, 58 episodes of The 100 have aired, concluding the fourth season . </P> <Table> <Tr> <Th_colspan="2"> Season </Th> <Th_colspan="2"> Episodes </Th> <Th_colspan="2"> Originally aired </Th> <Th_colspan="2"> Nielsen ratings </Th> </Tr> <Tr> <Th> First aired </Th> <Th> Last aired </Th> <Th> Rank </Th> <Th> Viewers (millions) </Th> </Tr> <Tr> <Td> </Td> <Td_colspan="1"> </Td> <Td_colspan="2"> 13 </Td> <Td_colspan="1"> March 19, 2014 (2014 - 03 - 19) </Td> <Td> June 11, 2014 (2014 - 06 - 11) </Td> <Td> 150 </Td> <Td> 2.59 </Td> </Tr> <Tr> <Td> </Td> <Td_colspan="1"> </Td> <Td_colspan="2"> 16 </Td> <Td_colspan="1"> October 22, 2014 (2014 - 10 - 22) </Td> <Td> March 11, 2015 (2015 - 03 - 11) </Td> <Td> 157 </Td> <Td> 2.46 </Td> </Tr> <Tr> <Td> </Td> <Td_colspan="1"> </Td> <Td_colspan="2"> 16 </Td> <Td_colspan="1"> January 21, 2016 (2016 - 01 - 21) </Td> <Td> May 19, 2016 (2016 - 05 - 19) </Td> <Td> 165 </Td> <Td> 1.94 </Td> </Tr> <Tr> <Td> </Td> <Td_colspan="1"> </Td> <Td_colspan="2"> 13 </Td> <Td_colspan="1"> February 1, 2017 (2017 - 02 - 01) </Td> <Td> May 24, 2017 (2017 - 05 - 24) </Td> <Td> 158 </Td> <Td> 1.47 </Td> </Tr> </Table>

When did season 4 of the 100 start