Sum will adjust to expanding range

I want to sum a range of values where the range will expand as new values are added to the end. For example, if I have values in A1 through A10, I can sum the values with =sum(a1:a10). However, if I add a value to A11, I have to edit the function to =sum(a1:a11). Each time I add a value to the end of the range I have to edit the sum function.

Is there a modification that I can make to the sum function so that it will automatically adjust to the new range?