- “A” is used when we're talking about only one thing of various. i.e.: A car, A house, A senator, A piece of pie - “The” is used to refer to something unique. i.e.: The moon, The king, The water, The Sahara desert Since there is only one president in the U.S.A., the right one is “The President”. It would be a different case if we were talking about a senator or a candidate for presidency, because there are more than just one of them.

"The"

Great question! "A" is used when we are talking about things in general terms e.g. a dog, a cat, a house (there is one of many of these things). We use "the" when we need to be specific e.g. the sun, the moon, the stars. Since there is only one president of the United States (not many), we need to say "the president".

Hi Pasha, We use “the” in this case, because we are talking about a certain position and the status it gives the particular person in that position.

What Alexander wrote. "A" is used for something more general, e.g. "A president once said 'blah blah blah'." We use "a" because we don't know which president said it. BUT "Yesterday, the President of the US said 'blah blah blah.'" We know which President.