Use of apostrophe vs single quote/backtick

Template literals are enclosed by the back-tick ` (grave accent) character instead of double or single quotes.

Template literals / string literals in javascript use the back tick. They are an E6 feature that is simply syntactic sugar for concatenation. Template literals are widely supported in modern browsers and are supported in nodejs. When not using templates you should either use double (") or single (') quotes.

MDN has documentation that will give more information on template literal use: Template literals

The backticks are necessary for the string interpolation to work. This is an ES6 feature called template interpolation: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals.

Sometimes it will be available to you, but it is still far from widespread in terms of browser support https://caniuse.com/#feat=template-literals. Get familiar with it and use it when you can!