Allows to the user to re-calculate or update extent of feature class from Arctoolbox.
Sometimes when you zoom to your data, the zoom doesn't represent the maximum rectangular extent of the features.
Bounding rectangular may be bigger than extent of all the feature.
For example, it often happens with CAD Data because there is a reference from 0,0.
Now, you can update extent of feature class from ArcToolBox or using a ModelBuilder.
Via Elpidio I F Filho