  We present version 8 of the CHIANTI database. This version includes a large
amount of new data and ions, which represent a significant improvement in the
soft X-ray, EUV and UV spectral regions, which several space missions currently
cover. New data for neutrals and low charge states are also added. The data are
assessed, but to improve the modelling of low-temperature plasma the effective
collision strengths for most of the new datasets are not spline-fitted as
previously, but are retained as calculated. This required a change of the
format of the CHIANTI electron excitation files. The format of the energy files
has also been changed. Excitation rates between all the levels are retained for
most of the new datasets, so the data can in principle be used to model
high-density plasma. In addition, the method for computing the differential
emission measure used in the CHIANTI software has been changed.
