A point-of-control is the price with the most activity in a session. If a later session never trades back to it, it remains naked. Traders keep these levels on the chart for days or weeks.
The reasoning is that the most heavily traded price of a session represents where a large amount of inventory was established, so participants have reason to defend or revisit it. Untouched levels accumulate as reference points.
It is worth being sceptical about how much of this is real and how much is attention. Naked POCs get hit eventually for the trivial reason that markets oscillate, and there is no timescale attached to the claim. Use them as potential targets rather than as evidence about direction.
Related: point-of-control, market-profile, value-area, high-volume-node