<P> The Big Bang Theory is an American comedy television series created and executively produced by Chuck Lorre and Bill Prady . Like the name of the series itself (with the exception of the first episode "Pilot"), episode titles of The Big Bang Theory always start with "The" and resemble the name of a scientific principle, theory or experiment, whimsically referencing a plot point or quirk that is stated in that episode . </P> <P> In March 2017, CBS announced that the series was renewed for two more years, leading the show to a total of 12 seasons . The eleventh season premiered on September 25, 2017 . As of May 10, 2018, 255 episodes of The Big Bang Theory have aired, concluding the eleventh season . There was also an unaired pilot which CBS did not broadcast . </P> <Table> <Tr> <Th_colspan="2"> Season </Th> <Th_colspan="2"> Episodes </Th> <Th_colspan="2"> Originally aired </Th> <Th_colspan="4"> Nielsen ratings </Th> </Tr> <Tr> <Th> First aired </Th> <Th> Last aired </Th> <Th> Viewers (millions) </Th> <Th> Viewers rank </Th> <Th> 18--49 rating / share </Th> <Th> 18--49 rank </Th> </Tr> <Tr> <Td> </Td> <Td_colspan="1"> </Td> <Td_colspan="2"> 17 </Td> <Td_colspan="1"> September 24, 2007 (2007 - 09 - 24) </Td> <Td> May 19, 2008 (2008 - 05 - 19) </Td> <Td> 8.31 </Td> <Td> 68 </Td> <Td> 3.3 / 8 </Td> <Td> 46 </Td> </Tr> <Tr> <Td> </Td> <Td_colspan="1"> </Td> <Td_colspan="2"> 23 </Td> <Td_colspan="1"> September 22, 2008 (2008 - 09 - 22) </Td> <Td> May 11, 2009 (2009 - 05 - 11) </Td> <Td> 10.03 </Td> <Td> 40 </Td> <Td> N / A </Td> <Td> N / A </Td> </Tr> <Tr> <Td> </Td> <Td_colspan="1"> </Td> <Td_colspan="2"> 23 </Td> <Td_colspan="1"> September 21, 2009 (2009 - 09 - 21) </Td> <Td> May 24, 2010 (2010 - 05 - 24) </Td> <Td> 14.22 </Td> <Td> 12 </Td> <Td> 5.3 / 13 </Td> <Td> 5 </Td> </Tr> <Tr> <Td> </Td> <Td_colspan="1"> </Td> <Td_colspan="2"> 24 </Td> <Td_colspan="1"> September 23, 2010 (2010 - 09 - 23) </Td> <Td> May 19, 2011 (2011 - 05 - 19) </Td> <Td> 13.21 </Td> <Td> 13 </Td> <Td> 4.4 / 13 </Td> <Td> 7 </Td> </Tr> <Tr> <Td> </Td> <Td_colspan="1"> 5 </Td> <Td_colspan="2"> 24 </Td> <Td_colspan="1"> September 22, 2011 (2011 - 09 - 22) </Td> <Td> May 10, 2012 (2012 - 05 - 10) </Td> <Td> 15.82 </Td> <Td> 8 </Td> <Td> 5.5 / 17 </Td> <Td> 6 </Td> </Tr> <Tr> <Td> </Td> <Td_colspan="1"> 6 </Td> <Td_colspan="2"> 24 </Td> <Td_colspan="1"> September 27, 2012 (2012 - 09 - 27) </Td> <Td> May 16, 2013 (2013 - 05 - 16) </Td> <Td> 18.68 </Td> <Td> </Td> <Td> 6.2 / 19 </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td_colspan="1"> 7 </Td> <Td_colspan="2"> 24 </Td> <Td_colspan="1"> September 26, 2013 (2013 - 09 - 26) </Td> <Td> May 15, 2014 (2014 - 05 - 15) </Td> <Td> 19.96 </Td> <Td> </Td> <Td> 6.2 / 20 </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td_colspan="1"> 8 </Td> <Td_colspan="2"> 24 </Td> <Td_colspan="1"> September 22, 2014 (2014 - 09 - 22) </Td> <Td> May 7, 2015 (2015 - 05 - 07) </Td> <Td> 19.05 </Td> <Td> </Td> <Td> 5.6 / 17 </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td_colspan="1"> 9 </Td> <Td_colspan="2"> 24 </Td> <Td_colspan="1"> September 21, 2015 (2015 - 09 - 21) </Td> <Td> May 12, 2016 (2016 - 05 - 12) </Td> <Td> 20.36 </Td> <Td> </Td> <Td> 5.8 / 19 </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td_colspan="1"> 10 </Td> <Td_colspan="2"> 24 </Td> <Td_colspan="1"> September 19, 2016 (2016 - 09 - 19) </Td> <Td> May 11, 2017 (2017 - 05 - 11) </Td> <Td> 18.99 </Td> <Td> </Td> <Td> 4.9 / 19 </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td_colspan="1"> 11 </Td> <Td_colspan="2"> 24 </Td> <Td_colspan="1"> September 25, 2017 (2017 - 09 - 25) </Td> <Td> May 10, 2018 (2018 - 05 - 10) </Td> <Td> 18.63 </Td> <Td> </Td> <Td> 4.4 </Td> <Td> 5 </Td> </Tr> </Table>

Total number of seasons in big bang theory
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