What is meant by case sensitive language?

1. Uppercase and lowercase letters are distinguished.
2. Lowercase letters are converted into uppercase letters.
3. Uppercase letters are converted into lowercase letters.
4. Uppercase and lowercase letters are treated to be same.

Uppercase and lowercase letters are distinguished.

Reason — A case-sensitive language treats uppercase and lowercase letters as distinct. This means that identifiers such as Variable, variable and VARIABLE would be considered different.