Why do some Emacs lists start with a backtick instead of a comma?

Lists that start with a ` end up having values interpolated.

Compare the following two examples:

'(,(concat "Hello, " "World"), "Nice to meet you?")
; (,(concat "Hello, " "World")
;   ,"Nice to meet you?")

As you can see, we got the exact same list that we defined when starting with a '

How about using a `?

`(,(concat "Hello, " "World"), "Nice to meet you?")
; ("Hello, World" "Nice to meet you?")

The concat expression is evaluated and we get back two strings!