Student or Learner
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?
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.