Integrated Lights-Out, or iLO, is a proprietary embedded server management technology by Hewlett-Packard which provides out-of-band management facilities. The physical connection is an Ethernet port that can be found on most Proliant servers of the 300 and above series.
iLO makes it possible to perform activities on an HP server from a remote location. The iLO card has a separate network connection (and its own IP address) to which one can connect via HTTPS.
References: https://en.wikipedia.org/wiki/HP_Integrated_Lights-Out