What's the u prefix in a Python string?

Question

Like in:

u\'Hello\'

My guess is that it indicates \"Unicode\", is it correct?

If so, since when is it available?

Answer 1

My guess is that it indicates "Unicode", is it correct?

Yes.

If so, since when is it available?

Python 2.x.

In Python 3.x the strings use Unicode by default and there's no need for the u prefix. Note: in Python 3.0-3.2, the u is a syntax error. In Python 3.3+ it's legal again to make it easier to write 2/3 compatible apps.