The NIST Database of Cross Sections for Inner-Shell Ionization by Electron or Positron Impact provides cross sections for ionization of the K shell and of the L and M subshells of neutral atoms of the elements, from hydrogen to einsteinium, by electrons or positrons, for projectile energies from the ionization threshold to 1 GeV. These cross sections were calculated from a combination of the relativistic distorted-wave and the plane-wave Born approximations. Extensive comparisons have been made of the calculated cross sections for inner-shell ionization by electron impact with available experimental data that satisfied mutual-consistency checks. These comparisons showed that the overall root-mean-square deviation between measured and calculated cross sections was 10.9 % [X. Llovet, C. J. Powell, A. Jablonski, and F. Salvat, J. Phys. Chem. Ref. Data 43, 013102 (2014)].