Does anyone know what the lines in digitals mean?

[Cxitlin119]

I’ve taken 2 test and both have faint lines so I took a digital and it says not pregnant. I’ve seen loads of people say 3 lines means pregnant but I’m so confused with how they work

I’m assuming the digital was negative, I found this on google and I’m pretty sure there’s always three lines. The digital actually reads positive at 10miu. Looks like the line on the top strip has to be darker than the one on the bottom. I do see a shadow on the other test. Best to wait a couple of days and test again.