Basically, for a function, you can think of **domain** as "what you can put in that will result in an answer" or the x's and
**range** is "what you get out", the y's. Another way to define this would be that the
**domain** is all the possible inputs, and the **range** is all the possible outputs.

For an example, lets use the function **y=x**^{2}.

The **domain** of this function is **all the real numbers**.

Why? Because you can have any real number be x and you will get an output.

Some examples:

If x=0, then y=(0)^{2}=0

If x=4, then y=(4)^{2}=16

If x=-9, then y=(-9)^{2}=91

If x=4.34, then y=(4.34)^{2}=18.8356

and so on.

And it can be seen that the **range** of this function is **
all positive real numbers**.

Now, lets change the function just a bit, **y=1/x**^{2}

The **domain** is now **all real numbers
***except* for 0.

Why? Because when x=0, the function is not defined, therefore, there is no result.

Another example of this would be a function similar to **y=1/(x-3)**

In this case, the **domain** is **all real numbers
***except* 3.

Why? Again, if x=3, the denominator would be 0, and you would not get a valid result.

Hope this helps!