What is taking the first letter of each word in a list of items and using those letters to spell a name or thing called?

This technique is called an acronym or an acrostic, depending on the context. An acronym typically forms a new Word from the initial letters of a series of Words, while an acrostic is a more poetic form where the letters at the beginning of each line or Word spell out a Word or name. Both methods are used for memorization or creative expression.