What is underscore

Answer 1

An underscore is the "_" character, if that's what you're asking...

Answer 2

Since you have "data-types" in your tag, an underscore "_" is a char (character).

It's usually used to make variables more readable and are put instead of a space so that your variable is still one word and the code can compile.

Answer 3

Please clarify your question, so someone can help you. What language? What is the context? If you don't clarify, this will be requested to be removed.