An overview of the results of the Near-IR S0 galaxy Survey ( NIRS0S ) is presented .
NIRS0S is a magnitude ( m _ { B } \leq 12.5 mag ) and inclination ( < 65 ^ { o } ) limited sample of \sim 200 nearby galaxies , mainly S0s , but include also Sa and E galaxies .
It uses deep K _ { s } -band images , typically reaching a surface brightness of 23.5 mag arcsec ^ { -2 } .
Detailed visual and photometric classifications were made , for the first time coding also the lenses in a systematic manner .
The main analysis methods include 2D multi-component decomposition approach , and Fourier analysis of the non-axisymmetric structures .
As a comparison sample , a similar sized spiral galaxy sample with similar image quality was used .
The main emphasis were to study whether the S0s are former spirals in which star formation has been ceased , and also , how robust are bars in galaxies .
Based on our analysis the Hubble sequence was revisited : following the early idea by van den Bergh we suggested that the S0s are spread throughout the Hubble sequence in parallel tuning forks as spirals ( S0a , S0b , S0c etc . ) .
This is evidenced by our improved bulge-to-total ( B / T ) flux ratios in the S0s , covering the full B / T range , reaching small values typical to late-type spirals .
The properties of bulges and disks in S0s were found to be similar to those in spirals and also , the masses and scale parameters of the bulges and disks to be coupled .
It was estimated that the spiral bulges brighter than -20 mag in K -band are massive enough to be converted into the bulges of S0s merely by star formation .
Bars were found to be fairly robust both in S0s and spirals , but inspite of that bars might evolve significantly within the Hubble sequence .