Is it a LED or an LED?

Answer 1

An LED. (el-ee-dee)

You would put 'an' before the word LED because the letter L is pronounced with a leading vowel sound, as "EL". It is not a vowel that determines the usage, but the vowel sound. Similarly, the silent H in "hour" means that 1 hour is "an hour".

The reverse is found in words such "union", where the YOU sounds like a consonant, and you say "a union."

Sounded-out acronyms

When an acronym is sounded out as a word, rather than individual letters, then it can use the article matching the word sound, as with a NASA probe or a NORAD radar station.