Microsoft Windows Excel

'Window' is operating system whereas "office' is application software, both from Microsoft. In the past most PCs (almost all) were preloaded with microsoft office, and most users don't make a distinction between Window and Office. They think 'office' is part of 'window', but apparently they are not. Microsoft likes to bundle everything into Windows and captures the market since 'window' dominates the market.
'Office' includes Access, Word, Excel and Powerpoint.

Microsoft Office已經包括埋Excel在內。