Function of sum

[LMelo1]

I wonder if has a function that you can add a column but obeying the criteria of another column. Ex:
___C___D___E___ F
2...xx__10_______30
3...yy__15
4...xx__20
5...yy__25
6...zz__30
...
...
n...zz__35

Then , in F2, obtain the sum of column D for all values in column C with "xx". (In case: 10 + 20 = 30)
Thanks
Luiz Melo