NY, CA, IL etc.

[peppy_man]

New York is often called NY, California CA and Illinois IL.
How do you call NY, CA and IL?
'Shortened forms'? 'Contracted forms'? Or is there any other?
Thank you.

[rewboss]

The United States Postal Service calls them "State abbreviations".

People disagree about what words like "contraction" and "acronym" mean, but I usually follow this scheme:

An initialism is an abbreviation made up of the initial letters of the words they stand for; e.g. BBC for British Broadcasting Corporation -- NY for New York is another example.

An acronym is an initialism which is pronounced as a single word; e.g. NATO for North Atlantic Treaty Organisation.

A contraction is a word or words made shorter by leaving out some letters; e.g. flu is a contraction of influenza; CA is a contraction of California.

So in fact, some state abbreviations are initialisms, others are contractions.