Difference between “A” and “The”
"The", as mentioned earlier, is used to give information about particular or known nouns. These are usually things that have been mentioned before or that the listener is familiar with. On the other hand, "A" or "an" is used to talk about things which are not particular. Usually, these are things that haven't been mentioned before or that the listener is unfamiliar with.
For example, study these sentences:
I went to see a tattoo artist.
The tattoo artist has given me an appointment next week.
It is clear that in the first sentence, the speaker did not go to see a particular tattoo artist. He/she went to see any tattoo artist and was speaking to a friend about the same. The tattoo artist in this case has either not been mentioned before or is not that important, and therefore their identity is unknown.
Whereas in the second sentence, the speaker refers to the tattoo artist that had already been mentioned before. The identity is already known, therefore, “the” has been used to refer the tattoo artist.
Usage of ‘the’