What is Microsoft Office Specialist for Excel exam? Microsoft Office Specialist (also known as MOS) is a certificate that can be earned if you pass an exam. Microsoft Office Specialist has exams for different Office products, which include Microsoft Word, Powerpoint, Excel, Access, Outlook, SharePoint, OneNote. Microsoft Word and Excel are slightly different, each of them have two levels, one is Core level and the other is Expert level. If you take a specific combination of exams, you can...