How to use articles 'a', 'an', and 'the' in English? - Basic English Grammar lesson
English articles ("a", "an", and "the") come before nouns. They help to communicate which thing you're talking about, similar to words like "this", "my", and "all". And they're confusing to a lot of English learners.
Articles are really, really hard!
If your native language doesn't use articles, they can be really confusing. The truth is, you might never completely master articles. Most non-native English speakers don't, even know if they're quite fluent and have spoken English for a very long time. That's mostly OK. Mistakes with articles don't usually get in the way of communication. Your listeners or readers will usually be able to figure out what you mean by guessing whether you meant "a thing" or "the thing".
So while you should try to improve your skill with articles, you shouldn't worry much about them. This video lesson by Niharika will clear your basic doubts for using articles correctly.