A vs. The

 

 

When you’re talking about one thing in a general way, use the indefinite article “a”.

 

But if you’re talking about something everyone in the conversation is familiar with  then use “the”.

 

For example,

 if I say “let’s watch a movie”, 

I’m suggesting that we watch any movie. 

We don’t know which movie we’re going to watch yet – I just want to watch something, anything.

 

 However, if I say “let’s watch the movie”,

 I’m referring to a specific movie that you and I have already talked about watching together.