David H. Ringstrom, CPA, is the author of Microsoft 365 Excel for Dummies, and nationally recognized instructor who has taught over 2,500 live webinars. His Excel courses are based on over 30 years of consulting and teaching experience. David’s catchphrase is “Either you work Excel, or it works you,” so he focuses on what he sees users don’t, but should, know about Microsoft Excel. His goal is to empower you to use Excel more effectively. David has authored or co-authored 8 books, including Exploring Microsoft Excel's Hidden Treasures and QuickBooks Online for Dummies, and Idiot's Guide to Introductory Accounting.