Work together on the same worksheet
When you’re working with others in Excel Online, you can edit the worksheet as you usually would. When others edit the worksheet, Excel Online shows their presence and the updates right away. This only works when everyone is working in Excel Online. If anyone opens the workbook in Excel desktop, others won't be able to edit the workbook at the same time in Excel Online.
See this external link, Top tips for working in Excel Online.
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