what Event is triggered when user adds/deletes rows?

I'm trying to create VBA conditional formatting (more than 4 formats needed).

One of my formats involves alternating row colors, e.g.:

If iCell.Row Mod 2 = 0 Then
     iCell.Row.Interior.Color = RGB(128, 255, 128)
End If

If the user inserts or deletes rows, then I'll have to update everything below the change. For which Worksheet Event should I be writing code and what range will it pass to my subroutine so that I know where to work the changes?