DVI uses the same digital video signal as HDMI, and passive cables or adapters make it easy to switch between them. I have an older graphics card, one with 1 HD

DVI uses the same digital video signal as HDMI, and passive cables or adapters make it easy to switch between them. I have an older graphics card, one with 1 HDMI port, 1 VGA port, and 1 DVI port. I've got the HDMI and DVI plugged into 2 HDMI monitors. DVI can also carry an analog video signal. The DVI out on my graphics card can use a passive cable/adapter to VGA. I think DVI was intended as an intermediate standard, so people could use their existing VGA monitors with the possibility of upgrading to digital in the future.