Photo for H1 visa stamping

[rajgot]

This may seem like a very basic question, but i couldn't figure it out. Please help clearing my doubt.

In many places on internet it says we need a digital photo and paper photo. I already filled DS160 online and it never asked me to upload photo. I have in-person interview appointment.
- Why do i need digital photo? If digital photo is need should i carry it on USB stick or something to interview?
- During OFC they will take photo, is that going to be used in visa stamp?

Thanks