In JavaScript, any number of characters inside quotation marks is called a string, as in a "string of text". String values are just text, and are typically used for displaying text on a web page, like this paragraph.
let someString = "This is a string!";
let threeString = "3"; // this is a string value, because of the quotation marks
let threeNumber = 3; // this is a number value, because there are no quotation marks.
Sometimes you might have two strings and might want to join them together. The action of fusing string values together with a plus sign is called concatenation.
let someString = "This is a string!";
let otherString = "This is another!";
let concatinatedString = someString + otherString;
The output of concatinatedString would be:
This is a string!This is another!
If you wanted to put a space after the first string, you could concatenate a space using quotation marks, along with the variables, like this:
let concatinatedString = someString + " " + otherString;
// which results in:
This is a string! This is another!
Another way of doing this is to include the space within one of string variables.
let someString = "This is a string! "; // see the space after the exclamation point?
let otherString = "This is another!";
let concatinatedString = someString + otherString;
// results in:
This is a string! This is another!
// Or...
let someString = "This is a string!";
let otherString = " This is another!"; // see the space at the start of the string?
let concatinatedString = someString + otherString;
// results in:
This is a string! This is another!
Another example... what do you think happens here?
let stringValueIsNotFive = "3" + "2";
The resulting string value is "32", not "5", because the plus symbol is not adding them, they are just simple text, and the plus sign is just concatenating [joining] the two string values together into one string value.
A word of caution here. If you try to add a number with a string, the answer will be automatically converted into a string. If you have a variable in your code that's intended to be a number, but ends up with a string value, it can be hard to troubleshoot. So, try to be aware of numbers that are actually strings, and try to avoid adding with them.