When Excel files can be opened in browser?

In open dialog box (of an Excel 2010 file) in path File > open, there is a drop-down list for Open button. One of them is, open in browser. When Excel files can be opened in browser (Web browser, e.g., Chrome) please?

Thanks for the answer. It's not what I said. :)
I found that here
When Excel files can be opened in browser? - Super User

It just opens the HTML files apparently. That's all mate:)