The PARMEST package in Stata helps create new datasets with important information about model parameters. It includes modules like parmest, parmby, parmcip, and metaparm. Parmest generates a dataset with details on each parameter, while parmby does the same but for different groups. Parmcip calculates confidence intervals and P-values. Metaparm combines parameters from separate analyses into new combinations with confidence intervals. The output datasets can be saved, listed, or plotted for further analysis.