[android] What is android:ems attribute in Edit Text?

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What means Ems? (Android TextView)

In EditText there is an attribute named android:ems. The description is "Makes the EditText be exactly this many ems wide"

What does ems mean?

An "em" is a typographical unit of width, the width of a wide-ish letter like "m" pronounced "em". Similarly there is an "en". Similarly "en-dash" and "em-dash" for – and —

-Tim Bray