Hello World! I'm talking about variables.
A variable is a named location in memory.
For instance we might have a variable named students which has a value of 23.
That would be an integer: a  whole number with no decimal places.

We have the name hourlyRate with a value of 9.75.
and that the double.
Also notice that the name has an uppercase R.
We're not allowed to have any spaces in variable names
We separate two words by making each word begin with a capital letter.
The first letter of the variable should be a lowercase letter.
This style, with the uppercase and for the second and third word, and so on,
is called camel case. It makes it easy to read.
Even though you can't have space, you can see that as two words.

Another type that we have is Boolean,
and it can only have values of true or false.

Here are some more examples of integers:
We have students.  The number of students in class can't have a decimal place.
quantity: If you go to the store and buy a number of items it's usually an integer.
If we're counting how many times something happens that would also be an integer.

The other type we talked about is a double.
That's a number with decimal places.
Anything having to do with money is always double.
But if in doubt and we don't know exactly what the numbers are going to be
It's better to pick double that to pick integer.
A double can have an integer value we would just write 4.0 instead of 4 for instance.

Strings are words or sentences.
Strings are also things like phone numbers even though that's all digits,
We're not really treating that as a number.
You're not going to find the average phone number of all your friends for instance.

Boolean are variables that have a value of true or false.
Some examples might be freezing, ready, married, raining and so on.