Web Applications SE has tags for the most popular web aplications like google-search, facebook among many others.
Include in your questions tags related to the web application that you are using, not include tags based on words used to describe the problem. I.E. if you have problems when using Google for searching for a discussion forum specialized in fashion topics for kids, use google-search but don't use forum.
If you will ask a questions about a spreadsheet formula in Google Sheets, use google-sheets and formulas. Only include microsoft-excel too if your question is about compatibility issues of formulas of a spreasheet that is being edited in Google Sheets and Microsoft Excel.
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