@Strigoaica That is correct. "Miss" is like the German "Fräulein," which also has almost disappeared in use in Germany. It defines an unmarried woman. "Mrs," on the other hand, is clearly defining a married woman. So, modernly, people thought it would be more polite to leave the marital status out of the discussion and invented "Ms." as a generalized address. Nowadays here we always use "Ms." when we address someone we don't know in writing. Of course, this is written English and it is always used with the name.
To address someone as "Miss" without her name, has the same connotation as doing so in German, using "Fräulein!" It was typically used in restaurants and cafes when calling a waitress, as in "Fräulein! Zahlen bitte!" and nowadays is regarded as rude and not political correct. It is regarded as condescending. In my wife's school, where she is teaching, it would never be accepted if used to address a teacher. Kids would either have to say: "Miss Johnston, could you please have a look here?" or "Ma'm, could you help me with this, please?"
The same goes for addressing gentlemen: You never use "Mister" without the name, it is regarded, in the same way, as rude. A teacher will always be addressed as "Mr. Berger" or "Sir."