Hide: checks for a background cell colour on row one column headings to determine the columns to hide. Columns without a background colour will be hidden.
Unhide: makes visible any hidden columns on the open worksheet
Select: will select cells top-down to cover the data range within one or more adjacent columns. The selection will ignore blank cells and cover the complete data range. whereas the ctl+shift+down-arrow selection key method will only extend the selection as far as the first blank cell.