How To use A, An & The In English

A & An - Use for a general thing (one of many)
Example : I want to buy a bike
                 He is eating an orange

The - use it for specific thing
Example : The boy who is wearing a black dress is handsome
                 We like the red car

Use "An" if the word starts with the sound of A, E, I, O, U:
•An apple
•An eel
•An ice cream 
•An orange
•An university

Use "A" if the word starts the sound of any other letter
•I drink a cup of coffee
•Jack is a nice person

Use "The" for specific thing
•I am going to eat the chocolate cake
•Billy loves to eat the pizza from Pizza Hut Restaurant