What does the C mean on hCG pregnancy test?

There is no "C" on an hCG pregnancy test. However, there are two lines on an hCG pregnancy test that indicate a result -- a test line labeled "T" and a control line labeled "C".

If only the control line is visible on the test within the test's time window, the test result is negative. If both the test and control lines are visible, the result is positive. If neither line appears on the test, it is considered void.