On a pregnancy test does one or two lines mean you're pregnant?

On most pregnancy tests:

1 line means: if the one line that you see is the control line, your test is negative; if the one line that you see is the test line, your test is invalid, and you must use a new test.

2 lines means: if you have two lines on a pregnancy test then your test is positive; if one line is lighter than the other, your test result is still positive.