What is the difference between these two sentences:
Tom was hiding in the barn.
Tom was hiding in a barn.
What is the difference between these two sentences:
Tom was hiding in the barn.
Tom was hiding in a barn.
Here are two examples:
Tom had been shot down over occupied France and was trying to get back to England. One night he was hiding in a barn.
When the police came to his father's farm Tom was hiding in the barn.
The difference is this:
In the first case the context does not identify the specific barn, it's just one that Tom found on his travels. As the barn is not identified we use the indefinite article a.
In the second case the barn is identified as being the one on Tom's father's farm. Since it is identified we use the definite article the.
If there was more than one barn on Tom's father's farm we would either have to use the indefinite article and say "When the police came to his father's farm Tom was hiding in a barn" or identify the specific barn by saying "When the police came to his father's farm Tom was hiding in the big barn".