Too Long; Didn't Read
Before ES6(ECMAScript 2015), we have used single quotes('...') and double quotes('...") to wrap string literals. With ES6, we have got template literals that allow embedding expressions. Template literals are enclosed by the backtick (`) characters instead of single or double-quotes. This is much better and favorable for developers to use. The tag function is usually a function that precedes a template literal to help you in manipulating the output. It's fine if you find it confusing. We will understand it in a few simple steps.