What are concrete nouns?

They are nouns that you can see or touch

Concerte nouns are a type of nouns that are tangible, countable and are sensible. In contrast to abstract nouns, these abstract nouns can't be sensed, moreover only ideally perceived whereas concrete nouns are something that can be sensed or sensation to perception is acknowledged.

Some examples are:

1. The books are on the shelf.

Books here are concrete nouns

2. Knowledge and faith are abstract nouns.