How do you use the word the?

Note that we use a in front of words that start with a consonant sound (a horse, a carrot) and an in front of words with a vowel sound (an apple, an elephant). We often use a when we mention something for the first time, and then change to the when it is clear which thing we are talking about: He was talking to a man.

For More Information Please Refer: https://dictionaryblog.cambridge.org/2015/08/19/a-an-and-the-how-to-use-articles-in-english/