Here is my delima

In column one, a person can input their ID number. In Column two, they
input hours of work.
Now there are multiple employees using the same sheet. What I want to
do is create a formula that adds all the values in column two that
correspond with each id number.

In other words, I want to make a formula that groups all the values
from the same ID number and adds them up.

Eventually I want to make a list that summarizes by employee id their
total hours worked.

Any sugguestions?