Why you should know: The ‘a’ vs ‘an’ conundrum is not about what letter actually begins the word, but instead about how the sound of the word starts.
For example, the ‘h’ in ‘hour’ is silent, so you would say ‘an hour’ and not ‘a hour’. A trickier example is Ukraine: because the ‘U’ is pronounced as ‘You’, and in this case the ‘y’ is a consonant, you would say “a Ukraine” and not “an Ukraine”.
Tip: when in doubt, sound it out(loud).
Thank you for coming to my TED talk.
A has an important role in language, its more than just filler. I am not an English expert, but I can look up some grammar to refresh myself a bit.
Which animal, how many eggs, what cat, what hat?
“The” has the opposite role.
There is a cat at the pond. The duck quacked at the cat.
In the first sentence, I introduced the existence of a cat. In the second sentence I referred specifically to the cat.
https://www.merriam-webster.com/dictionary/indefinite article
https://www.merriam-webster.com/dictionary/a#dictionary-entry-2