Variables: you can use a name (no spaces) to designate a memory location where you want to store a number or a text string.
The equal sign: just like Fortran, the equal sign means "make this equal to"
window.prompt pops up a small window with a text. The text is what you have inside the parentheses. Whatever the user types in that window will be a result that can be assigned to a variable.

Sample program:

<script language="javascript">

firstName=window.prompt("What is your first name?");

lastName=window.prompt("What is your last name?");

fullName=firstName+" "+lastName;

window.alert("Nice to meet you, "+fullName);

</script>

Try it!